I don't really see how edible socks made from food substances could be worn but it sounds like something you could give as a joke souvenir or something. I guess the most logical place for them to be bought would be a food store, most probably chocolate. They make chocolate everything just about.
But like seize_the_element said "Socks are already edible, just not very tasty."
I think it's sorta gross. I wouldn't wear my clothes and then eat them. It would be a waste, especially when I could get socks I could wear again and again.