Here are the directions for preparing acorn "meal" that I received today at an edible plants tour:

1. Shell acorns (white oak trees generally have the least bitter acorns, followed by red oaks then live oaks).
2. Allow shelled acorns to dry for a few hours in the sun
3. Grind acorns to fine powder
4. Mix acorn powder with boiling water
5. Place wet acorn powder in jelly bag (cotton bag) and squeeze out water
6. Repeat boiling water wash/squeeze until powder in no longer bitter
7. Spread powder out in thin layer in shallow pan to dry in sun or oven on low heat
8. The acorn flower will "cake" up during drying so it needs to be reground at this point
9. Store dried, ground powder in sealed glass jars where it'll keep indefinately.

-Blast