The Native Americans used acorn flour to make a type of flat bread, mush and soups. Acorn flour makes unleavened bread since it has no gluten. It can be used to make leavened bread, but must be mixed 50/50 with wheat flour.
Since acorn flour is high in oil it needs to be stored carefully and not be allowed to go rancid. Acorns in the whole shell will keep for several years if properly stored. Protect them from insects and varmints.
The tannic acid that is leached out has several uses. Tannic acid makes a good laundry detergent. However, it will color whites temporarily a slightly tan color.
Tannic water is antiviral and antiseptic. It can be used as a wash for skin rashes, skin irritations, burns, cuts, abrasions and poison ivy or poison oak. If you have a sore throat you can even gargled with tannic water or use it as a mild tea for diarrhea and dysentery. Externally dark tannic water can be used on hemorrhoids. Hides soaked in tannic water make better leather clothing. Using the brown water turned hides tan colored and that is why it is called tanning.