I'm currently polishing Impossible Beyond This Point (due out in 2013), the story of my in-law's move to the wilderness back in the 60s, and I ran across an account of a wild edibles meal my MIL made when her sister came to visit. The mainstay of the meal was acorns.
Did you know that you can eat acorns? That's right - they're not just for squirrels! I haven't done it recently, but we've made acorn meal in years gone by. Properly prepared, you can use chopped acorns in place of nuts or grind them into meal to make acorn mush or add to recipes. So if you have acorns available, gather some up and give them a try!
The first thing you have to do to make acorns edible is leach out the tannin. So shell them with a nutcracker or hammer and get the meats out. Then boil them and re-boil them and re-boil them again and again until the water is clear.
Use two pots and transfer the acorns from one to the other every 15 minutes or so. Bring fresh water to a boil in the pot without acorns while they're boiling away in the other pot. Make sure to keep them mostly boiling and DON'T put them in cold water. Keep this up until the cooking water stays clear and then dry them on a cookie sheet in the oven at about 250 degrees. Once they're mostly dry, chop or grind for use in recipes.
Another way to leach tannin
You can also leach out the tannin without boiling but it takes MUCH longer. First, grind up the meats into a fine meal. Put the ground meal in a basket or strainer lined with a clean muslin cloth and set atop a pot. Slowly pour in water to fill the basket and let it run through the ground acorn meal (same principle as a drip coffee maker). Check it often and add more water and empty the pot, as needed, until the water runs clear.
Alternatively, I suppose you could put the acorn meal in a clean muslin bag and tie it suspended in a stream. I also read that you can leach them in your toilet tank (clean it good first!) but I think I'll just stick to the boiling or drip filtering methods!