We ate in the Garden Grille Restaurant in Epcot last summer. It is a character meal served family style. Food is brought to your table by your server and you can have as much as you please. Characters are Mickey, Pluto and Chip 'n' Dale. Restaurant actually rotates whilst you are eating.
Buffet restaurants in the parks are:-
Epcot - Garden Grille and Restaurant Akershus in Norway.
MGM - Hollywood and Vine.
MK - Crystal Palace and Liberty Tree Tavern.
AK - Donald's Restonasaurus for breakfast.