Foie Gras is a world famous pâté made from specially fattened duck or goose livers. It comes in two distinct forms, Entier and Bloc.
Bloc is akin to more traditional pate, whereas Entier, the more expensive of the two, consists of whole liver lobes pressed together. The variety of foie gras made from duck liver (Foie Gras du Canard) is supposedly fuller and stronger tasting than the variety made from goose liver (Foie Gras d'Oie) which is meant to be richer and smoother.
The best foie gras in the world comes from the Dordogne region in midwestern France (also famous for its walnuts). The animals are fattened by force feeding them corn 2-3 times a day for several weeks, which leads to a distended/fatty liver, and damages the birds' health. Many people have an ethical problem with the way that the ducks are treated. Just to say I wouldn't want to have a tube shoved down my throat, and food pumped into me until I exploded.