Demeter

Demeter, or Demetra ("mother goddess" or "Mother of the Barley") was the Greek goddess of agriculture, pure nourishing young green earth, life-giving cycle of life and death, and marriage and protective sacred law. She is venerated as the "bringer of seasons" in the Homeric hymn, a subtle sign that she was worshiped long before the arrival of the Olympics. She and her daughter Persephone were also central figures of the Eleusinian mysteries that preceded the Olympic pantheon.
Demeter taught mankind the arts of agriculture: sowing seeds, plowing, harvesting, and so on. It was especially popular with rural people, partly because they were the most direct beneficiaries of aid, and partly because they were more conservative when it comes to save the old customs. Demeter was indeed instrumental in Greece's ancient religion. Relics own cult, as votive clay pigs, were made in the Neolithic. In Roman times, a sow was still sacrificed to Ceres when he had a death in the family, to purify the house.