Sacred day: March 17, the Liberalia
Liber, in his original Roman conception, was a god who presided over male fertility and especially the act of ejaculation. Like the name of his counterpart deity Libera, his name is derived from the Latin word that meant "liberation". A cult that worshiped the phallus in the name of Liber was practiced in Lavinium and later brought to Rome.
The phallus was carried about the countryside for a month in a wagon, repelling the Evil Eye and beaming fertility energy to women, animals, and land. During that month the citizens were allowed to indulge in saying obscene words in public until the phallus was carried through the forum and put in its resting place. Then respected matrons would crown it publicly with wreaths. A representation of the human phallus was kept in the temple of Liber.
Liber is the primordial spirit of libido and vitality. He is the essence of life; male procreative energy. Liber is the spirit of irrepressible fertility, invoked to stimulate agricultural abundance. At his most primordial stage, Liber was partnered with his female counterpart, Libera, the yin to his yang. He was then partnered with Ceres, spirit of grain.
Liber protects all kinds of seeds: plants as well as sperm. Eventually Liber was identified with Dionysus The name Liber is sometimes used to indicate Dionysus but they were originally distinct spirits.
The Liberalia is celebrated in his honor, along with his counterpart deity Libera, on March 17. Games held in Liber's honor were wild and raucous, as befitting his nature. A major part of the festival featured old women called sacerdotes Liberi wearing crowns of ivy selling honey cakes in the street. The cakes were fried on portable hearths, and a part of each cake bought was offered to Liber in the name of the buyer. Young men who have reached seventeen years of age also gain the right to wear man's clothing, the toga uirilis or liber, during this festival.
Offerings: His traditional offering was a cake called a libia formed from honey and olive oil; phallic imagery; fruits and vegetables; packets of seeds.
From: Encyclopedia of Spirits and other sources