About Dea Dia
Dea Dia is a very ancient Roman Goddess of the plowed field who is concerned with the fertility of the earth and the growth of the planted crops, especially grain. Her worship dates back to early times, and is of either Latin or Sabine origin; She is closely connected with the Arval Brethren, the ancient brotherhood of a dozen priests whose job it was to offer sacrifices for the robust health of the fields and crops.

Dea means "Goddess" and Dia seems to have it’s origins in words for "light" and "sky". If Dea Dia was originally a Sky-Goddess, then Her role in agriculture would be as the Goddess Whose light causes the crops to grow and mature.

Ambarvalia was a Roman agricultural fertility rite held at the end of May in honor of Dea Dia and Ceres. At these festivals they sacrificed a bull, a sow, and a sheep which, before the sacrifice, were led in procession three times around the fields. This is where the feast is supposed to have taken its name, ambio - I go round, and arvum - field.

Dea Dia’s priests, the Fratres Arvales (Arval Brethren) were a body of priests in ancient Rome who officiated this ceremony to guarantee good harvests.

For even more information visit:
http://www.thaliatook.com/OGOD/deadia.html http://en.wikipedia.org/wiki/Fratres_Arvale
http://en.wikipedia.org/wiki/Ambarvalia