Here is an extensive but by no means complete listing of edible flowers. I've listed them as follows:
Common name: (botonical name): Flavor - other information.
Please note: While the flowers mentioned in this edible flowers list are edible, other parts of the plants mentioned in this list may be poisonous. Know what you're eating! Also, be sure that no pesticides of other potentially harmful substances have been applied to the plant. Avoid plants growing along the sides of roads as they may have absorbed toxins from passing traffic.
Anise (hyssop Agastache foeniculum): Licorice
Apple (Malus spp.): Floral - Eat in moderation since flowers contain cyanide precursors
Arugula (Eruca vesicaria sativa): Peppery - once flowers form, the leaves become bitter
Basil (Ocimum basilicum): Herbal
Bachelor's button (Centaurea cyanus): Vegetal - petals are edible; the calyx is bitter
Bee balm (Monarda didyma): Minty, sweet, hot
Begonias Tuberous (Begonia X tuberosa): citrus-sour - Stems can be used in place of rhubarb. The flowers and stems contain oxalic acid and should not be consumed by individuals suffering from gout, kidney stones, or rheumatism.
Begonias Wax (Begonia cucullata): - The fleshy leaves and flowers are edible raw or cooked. They can have a slight bitter after taste and if in water most of the time, a hint of swamp in their flavor.
Borage (Borago officinalis): Cucumber - use sparingly - diuretic effects, combines well with nasturtiums
Broccoli (Brassica oleracea, Botrytis group): Spicy
Calendula (Calendula officinalis): spicy to bitter, tangy to peppery, sharp taste resembles saffron
Carnations (Dianthus caryophyllus - aka Dianthus): Sweet - cut petals away from the bitter white base of the flower.
Canary creeper (Tropaeolum peregrinum): Peppery
Chamomile (Anthemis nobilis, Chamaemelum noblis): Sweet apple - use in moderation, contains thuaone; ragweed sufferers may be allergic to chamomile
Chervil (Anthriscus cerefolium): Herbal
Chicory (Cichorium intybus): Slightly bitter
Chives (Allium schoenoprasum): Oniony - avoid eating whole flower; taste can be overwhelming
Chrysanthemum (Chrysanthemum coronarium): Tangy, slightly bitter - Always remove the bitter flower base and use petals only
Clover (Trifolium species): Sweet, anise-like, licorice - Raw flower heads can be difficult to digest.
Cornflower (Centaurea cynaus): slightly sweet to spicy, clove-like flavor.
Dame's Rocket (Hesperis matronalis): bitter - Often mistaken for Phlox. Leaves should be picked before the plant flowers. Seed can be sprouted and added to salads.
Dandelion (Taraxacum officinale): Sweet, honey-like, slightly bitter - use young flowers, mature flowers become bitter
Daylily (Hemerocallis spp.): Like sweet lettuce or melon - may act as a diuretic or laxative; eat in moderation. Not to be confused with other types of Lilies which may ontain alkaloids and are NOT edible.
Dianthus (Dianthus caryophyllus): Sweet, clove - remove the narrow base of the petals (bitter)
Dill (Anethum graveolens): Herbal
Elderberry (Sambucus canadensis): Sweet - do not wash flowers as it removes much of the flavor
English daisy (Bellis perennis): Slightly bitter
Fennel (Foeniculum vulgare): Mildly anise
Fuchsia (Fuchsia X hybrida): Slightly acidic - The berries are also edible.
Garden Sorrel (Rumex acetosa): Tart, lemony
Garlic chives (Allium tuberosum): Garlicky
Ginger (Zingiber officinale): Gingery
Gladiolus (Gladiolus spp): - nondescript flavor, vaguely like lettuce - remove anthers
Hibiscus (Hibiscus rosa-sinensis): Mild citrus, cranberry-like
Hollyhock (Alcea rosea): Mild nutty
Honeysuckle (Lonicera japonica): Sweet honey flavor - only the flowers are edible. Berries are highly poisonous - do not eat them!
Hyssop (Hyssopus officinalis): Strong herbal
Impatiens (Impatiens wallerana): Sweet
Indian Lotus (Nelumbo nucifera): Floral, Sweet (roots), Nutty (seeds) - Every part is edible. The stamens can be dried and made into a fragrant herbal tea. Seeds are roasted to make puffs called mahkanas. The plant's roots are ground up to make lotus meal.
Japanese plum (Prunus ‘Mume’): Sweet almond
Jasmine (Jasminum sambac and J. officinale): Sweet floral
Johnny-jump-up (Viola tricolor): Slightly minty, wintergreen - petals have little flavor unless the green sepals are included.
Lavender (Lavandula spp.): Strong floral - use sparingly due to intense flavor
Lemon (Citrus limon): Sweet citrus
Lemon verbena (Aloysia triphylla): Sweet citrus
Lilac (Syringa spp.): Very fragramt, slightly bitter. Has a distinct lemony taste with floral, pungent overtones. - The flavor of lilacs varies from plant to plant.
Linden (Tilia spp.): Sweet, Honey-like - Frequent consumption of linden flower tea can cause heart damage
Lovage (Levisticum officinale): Celery
Marigold (Tagetes patula): Citrus, bitter - Lemon Gem and Tangerine Gem have the best flavor
Marjoram (Origanum vulgare): Herbal
Mint (Mentha spp.): Minty - each type of mint has its own unique flavor
Mustard (Brassica juncea): Spicy - some people are highly allergic
Nasturtium (Tropaeolum majus): Peppery
Nodding onion (Allium cernuum): Oniony
Ocotillo (Fouquieria splendens): Sweet cranberry
Okra (Abelmoschus aesculentus): Mild, sweet
Orange (Citrus sinensis): Sweet citrus
Oregano (Origanum spp.): Herbal
Pansy (Viola x wittrockiana): Slight minty, sweet green or grassy flavor; petals have a mild flavor; whole flower has a wintergreen flavor
Passion flower (Passiflora spp.): Vegetal
Pea (Pisum sativum): Pea-like
Peony (Paeonia lactiflora): In China the fallen petals are parboiled and sweetened as a tea-time delicacy. Peony water was used for drinking in the middle ages. Add peony petals to your summer salad or try floating in punches and lemonades.
Phlox, Perennial Phlox (Phlox paniculata): Slightly spicy taste - It is the perennial phlox, NOT the annual, that is edible.
Pineapple (Feijoa sellowiana): Sweet tropical
Pineapple sage (Salvia elegans): Spicy, sweet, fruity, hint of mint and spice
Primrose (Primula vulgaris) Cowslip: Sweet bland
Radish (Raphanus sativus): Peppery, a distinctive, spicy bite - best used in salads
Redbud (Cercis canadensis): Pea-like
Red clover (Trifolium pratense): Sweet - raw clover flowers are not easily digestible.
Rose (Rosa rugosa or R. gallica officinalis): Flavors depend on type, color, and soil conditions. Flavor reminiscent of strawberries and green apples. Sweet, with subtle undertones ranging from fruit to mint to spice. NOTE: Be sure to remove the bitter white portion of the petals.
Rose of Sharon (Hibiscus syriacus): Mild
Roselle (Hibiscus sabdariffa): Mild citrus
Rosemary (Rosmarinus officinalis): Herbal
Runner bean (Phaseolus coccineus): Bean-like
Safflower (Carthamus tinctorius): Bitter
Sage (Salvia officinalis): Herbal
Scarlet runner bean (Phaseolus vulgaris): Vegetal
Scented geranium (Pelargonium spp.): Floral - the flavor is usually similar to the scent of the leaves, NOTE: Citronelle variety may not be edible.
Shungiku (Chrysanthemum coronarium): Slightly bitter
Signet marigold (Tagetes signata) (T. tenuifolia) Citrusy, herbal, similar to tarragon - may be harmful if eaten in large amounts; other marigolds are edible but have a tangy to bitter flavor
Snapdragon (Anthirrhinum majus): Delicate garden variety can be bland to bitter. Flavors depend on type, color, and soil conditions. Probably not the best flower to eat - best used as a garnish
Society garlic (Tulbaghia violacea): Sweet garlicky
Squash (Curcubita pepo spp.): Vegetal
Summer savory (Satureja hortensis): Herbal
Sunflower (Helianthus annuus): Flower is best eaten in bud stage when it has an artichoke flavor; petals of open flowers have a bitter-sweet flavor. The unopened flower buds can also be steamed like artichokes - pollen can cause a reaction for some people
Sweet woodruff (Galium odoratum): Fresh, sweet and grassy with a hint of nutty, vanilla flavor - Can have a blood thinning effect if eaten in large amounts
Thyme (Thymus spp.) Herbal
Tuberous begonia (Begonia x tuberhybrida): Citrus
Tulip (Tulipa spp.) Flavor varies from tulip to tulip, but generally the petals taste like sweet lettuce, fresh baby peas, or a cucumber-like texture and flavor. NOTE: If touching them causes a rash, numbness etc. Don't eat them! Don't eat the bulbs ever. If you have any doubts, don't eat the flower. Some people have had strong allergic reactions to them.
Violet (Viola odorata): Sweet floral
Water Lily (Nymphaea odorata): Both the young rolled up leaves and flowers can be boiled for five minutes and served with butter.
Winter savory (Satureja montana): Herbal
Yellow Pond Lily (Nelumbo lutea): The young leaves and flower buds were eaten as vegetables, roots baked and ground into flower, seeds eaten fried.
Yucca Petals (Yucca species): Crunchy with a mildly sweet taste (a hint of artichoke) - In the spring, they can be used in salads and as a garnish.
For an even more comprehensive listing of edible flowers visit Edible Landscape Design and Permaculture Wiki