Examine your acorns and discard any that have damaged shells, especially a dark hole or small circular scar on it about the diameter of a pencil lead, as those acorns will have worms.
Grind the acorns in a food processor or a blender with water: be liberal with the water, as the acorn puree is going to be rinsed several times.
Rinse out the tannins. Acorns contain tannic acid which is bitter and mildly poisonous. If you made acorn mush in a food processor, drape a cotton dishcloth over a deep bowl, pour in the mush and rinse it with warm water. Wring out the mush by bringing the corners of the towel together and twisting. Taste the mush; if bitter, repeat. If you ground the acorns in a blender, flush them with water. One method is to place them in a bowl of cold water and decant several times a day for as many days as it takes. Another method is to place the container under a stream of running water. You can also place the ground acorns in a pot of boiling water and change the water every 45 minutes for 6 to 7 hours of boiling. The amount of time it'll take to rinse out the tannins depends on which variety of oak tree the acorns come from.
Spread the mush on a cookie sheet and either leave it in the sun on a hot, dry day, put it in a dehydrator, or place it in the oven after baking and let the residual heat do the job. Stir the mush occasionally to speed the process. The mixture should clump and resemble ground beef.