In colonial days acorn flour was used to "stretch" out flour supplies. I don't expect it would give the same quality as wheat flour, but tough biscuits can and were made using it.
I've actually had rabbit, moose, deer, boar, quail, duck, turkey, chicken, beef, pork, various types of fish and seafood, but there's still a larger list of things I would like to try-Bear and Goose for example.
Even so, I know I'm still barely scratching the surface.
(Out of all of them, I think I preferred the boar, with duck a close second. Tastes like a cross between beef and pork and has a coarse, stringy texture excellent for slow cooking.)