Demeter, who took her name from Mother Earth, was one in the
generation of children born to Cronus and Rhea. Her name serves as a link to the Indio-European deities that the Hellenes brought with them. Gradually her divine personality was enriched with traits undoubtedly barrowed from pre-Hellenic deities, for she was never confused with Earth, or Gaia, who was considered a cosmic element.
Her province was over cultivated soil, especially land producing corn, which was why she was thought of as the goddess of vegetation, particularly corn. Her legends proliferated in areas of fertile plains, especially on the plain of Eleusis near Athens and Sicily, which long served as the granaries of the ancient world.
Poseidon was probably her first consort when he was still a horse-god, not choosing to live in the sea. To escape his pursuit Demeter disguised herself as a mere, but Poseidon immediately transformed himself into an horse, so the goddess' ruse failed. From their union two children were born: a horse called Arion (who later became the mount of Adrastus at the time of the war of the Seven against Thebes, and still later the property of Hercules), and a daughter who was simply called "the Mistress" as it was forbidden to speak her name.
In the Odyssey there is the mention of other lovers of Demeter, Iasion for instance (brother of Dardanus) by whom she bore a son named Plutus (Wealth). But Zeus being very displeased, when seeing the lovers from above, killed Iasion with a thunderbolt. Zeus was Demeter's other important consort of whom she bore Persephone, the dying and reviving daughter.
According to the Orphic tradition, one of the Greek "mystery" cults, Rhea as Demeter had forbidden to marry. Perplexed by this situation Zeus chose to rape his mother. Both Rhea and Zeus transformed themselves into serpents and coupled together. When Zeus enjoyed his daughter Persephone, he also assumed the serpent-like form and begot Dionysus.
The Athenians were ardent worshippers of Demeter. They claimed Triptolemus, a legendary ancestor, had invented the plough, and agriculture, and therefore civilization. It was he who stated the Eleusinian rites, where artists depicted riding in a chariot drawn by winged dragons holding a scepter and corn ears.
A.G.H. Sources: Grimal, Pierre, Larousse World Mythology, Secaucus, New Jersey, Chartwell Books, 1965, p. 120 Cotterell, Arthur, A Dictionary of World Mythology, New York, G. P. Putman's Sons, 1980, p. 138 http://www.themystica.com/mythical-folk/articles/demeter.html