Demeter

Roman Name: Ceres

Parents: Cronus and Rhea

Siblings: Zeus, Hades, Poseidon, Hera, Hestia

Relationships: She had relations with Zeus, who is the father of Persephone, Poseidon, who is the father of Despoena and Arion, and Iasion who is the father of Plutus, Philomenus, and Corybas.

Children: Persephone, who is the goddess of the underworld because Hades kidnapped her and made her his wife, Despoena, Arion, Plutus, Philomenus, Corybas.
God of: She was considered to be goddess of the earth and all growth and life. She was the one that introduced wheat to the humans. She also taught people how to farm and she provided all the nutrition on earth. 

Symbol: The ear of wheat and grain were her symbols because of the fact that she introduced wheat to the humans. 

Greatest Accomplishment: She introduced wheat to the humans and taught them how to farm so they would no longer be nomadic. She also helped families with fertility problems. 

Worst Deed: When her daughter was kidnapped by her brother Hades, who is the god of the underworld, she prevented anything from growing every winter which is when Presephone, her daughter, went to live with her husband in the underworld.