Demeter was the goddess in charge of the harvest.
Demeter's daughter Persephone made Demeter so happy that the crops grew high and healthy.
Hades the king of the Underworld felt restless one day so he took his three-headed dog Cerberus on a chariot ride to the mortal world.
Hades's dog Cerberus went to a young lady, the young lady then played with the three-headed dog, Hades then fell in love with Persephone, Hades took his dog, his chariot, and Persephone with him to the Underworld.
Hades locked Persephone in a room, Demeter was mad and told Zeus, Zeus then sent Hermes to make a deal with Hades, the deal was that Persephone would have to marry Hades, and Persephone could only see Demeter 6 months of every year.
Demeter prepared flowers every Spring for Persephone when she came, when Persephone would leave Demeter would let the crops die in Winter.