Information can be found on this website: http://www.historyforkids.org/learn/greeks/religion/persephone.htm
Persephone is the goddess of the underworld in Greek mythology. She is the daughter of Zeus and Demeter, goddess of the harvest. Persephone was such a beautiful young woman that everyone loved her, even Hades wanted her for himself. One day, when she was collecting flowers on the plain of Enna, the earth suddenly opened and Hades rose up from the gap and abducted her. None but Zeus, and the all-seeing sun, Helios, had noticed it.
Broken-hearted, Demeter wandered the earth, looking for her daughter until Helios revealed what had happened. Demeter was so angry that she withdrew herself in loneliness, and the earth ceased to be fertile. Knowing this could not continue much longer, Zeus sent Hermes down to Hades to make him release Persephone. Hades grudgingly agreed, but before she went back he gave Persephone a pomegranate (or the seeds of a pomegranate, according to some sources). When she later ate of it, it bound her to underworld forever and she had to stay there one-third of the year. The other months she stayed with her mother. When Persephone was in Hades, Demeter refused to let anything grow and winter began. This myth is a symbol of the budding and dying of nature. In the Eleusinian mysteries, this happening was celebrated in honor of Demeter and Persephone, who was known in this cult as Kore.
Here is a different source of information on Persephone.
Zeus, the king of all the gods, had three sisters. Hera, his wife and sister, was the goddess of marriage and the queen of all the gods.
Hestia, another of his sisters, was a much loved goddess by the woman of Greece – Hestia was the goddess of home and hearth.
His third sister, Demeter, was in charge of the harvest. All the gods jobs were important. Demeter’s job was very important. If she was upset, the crops could die. Everyone, gods and mortals, worked hard to keep Demeter happy. What made her happy was enjoying the company of her daughter, Persephone.
Persephone had grown into a beautiful young woman, with a smile for everyone. One day, while picking flowers in the fields, Hades, her uncle, the god of the underworld, noticed her.
Hades was normally a gloomy fellow. But Persephone’s beauty had dazzled him. He fell in love instantly. Quickly, before anyone could interfere, he kidnapped Persephone and hurled his chariot down into the darkest depths of the underworld, taking Persephone with him.
Locked in a room in the Hall of Hades, Persephone cried and cried. She refused to speak to Hades. And she refused to eat. Legend said if you ate anything in Hades, you could never leave. She did not know if the legend was true, but she did not want to risk it in case someone came to rescue her.
Nearly a week went by. Finally, unable to bear her hunger, Persephone ate six pomegranate seeds. It seemed her fate was sealed. She would have to live in the Underworld forever.
Meanwhile, back on earth, Zeus was worried about the crops. The people would die if the crops failed. If that happened, who would worship Zeus? He had to do something. Zeus did what he often did. He sent Hermes, his youngest son, the messenger, to crack a deal, this time with Hades.
Even as a baby, Hermes was great at making deals. Everyone knew that. But this deal might be the challenge of his life. His uncle Hades, king of the underworld, was really in love. This was no passing fancy.
When Hermes heard that Persephone had eaten six pomegranate seeds, he had to think quickly. The deal he made with Hades was that if Persephone would marry Hades, she would live as queen of the underworld for six months out of the year. However, each spring, Persephone would return and live on earth for the other six months of the year. Hades agreed. Zeus agreed. Persephone agreed. And finally, Demeter agreed.
Each spring, Demeter makes sure all the flowers bloom in welcome when her daughter, Queen of the Underworld, returns to her. Each fall, when Persephone returns to Hades, Demeter cries, and lets all the crops die until spring, when the cycle starts again.