Cheeks are a great buy. Cheap and full of flavour. Cook slowly. Couple of hours.
You can also get fish cheeks, and the great George Lassalle has a recipe for cod cheeks. Needs to be a big fish, though...
As for calf's head, never had it, but after reading Anthony Bourdin, would love to:
I love eating animals as much as the next guy, but there's something macabre about peeling the face off a baby cow, sticking its bollocks inside the floppy result and setting about it with a knife and fork.