Xylokastro is a small seaside town at the southern side of the Bay of Korinth inbetween Patras and Korinth.
A woman working at the Carrefour supermarket told me that they sort out the vegetables and fruits in the morning. She also told me about gypsies that are coming in the morining to pick up the food. So be there early and expect competition. And ask yourself if your really need it. There might be people that need it more than you. (Oct 2014)
In the other supermarket (I forgot the name, but it's next to Carrefour) they have some boxes with discounted fruits and vegetables. Just ask for them. (Oct 2014)