Why does Persephone have a pomegranate in her hand in lots of pictures?

Persephone held a pomegranate in her hand because that was one main part of the seasons. Persephone ate the pomegranate meaning that she had to stay in the underworld for 6 months, thus Demeter's creation of the seasons. When Persephone is in the underworld this creates Fall and Winter. When she is reunited with her child, this creates Spring and Summer.