Cerealia

Cerealia (Cerialia)

April 19

Ceres was the ancient Roman goddess of grain and of harvests, often identified with the Greek goddess Demeter. People held festivals in her honor in various locations, but the Cerealia originated in Rome, where she was worshipped at her temple on the Aventine Hill along with two other deities, Liber (a fertility god) and Libera, his female counterpart. The temple became a center of activity for the plebeians, or common people, who usually suffered when there was a grain shortage.
The festival known as Cerealia was observed at various locations only by Roman matrons, who, for several days preceding the festival, abstained from wine and other carnal pleasures. People who were in mourning were not allowed to appear at the celebration. For this reason, the Cerealia was not observed after the Battle of Cannae, when 50,000 Roman troops were killed by Hannibal.
There is a theory that April Fools' Day is a relic of the ancient Roman Cerealia, also held in April. According to legend, when Ceres's daughter Proserpine was carried off to the underworld by Pluto, Ceres heard the echo of her screams and tried to follow her voice. But it was a fool's errand, for it was impossible to locate the echo's source.
The Thesmophoria was a similar festival observed in ancient Greece.

SOURCES:
AmerBkDays-2000, p. 247
ClassDict-1984, p. 140
DictRomRel-1996, p. 45
FestRom-1981, p. 102
OxClassDict-1970, p. 223
OxYear-1999, p. 160

Celebration day: Apr 19