What are the edible parts of groundnut?

What are the edible parts of the ground nut? So far all I have found on the internet is that the tubers are edible. I don't now if they are referring to the tubers in the ground or the parts of the stems that resemble Tudors when they become swollen. These parts were noted as holding the most nourishment for the plant itself. It also said that the punishment for picking ground nut was the stocks for the first offense and whipping for the second. (not with cream) I also wonder if that law is still on the books.