I'm aware of pre-european Californian societies whose main calorie crop was acorns, rendered edible by soaking after crushing to remove irritating tannins and then cooked, and sometimes preserved by soaking in various other substances.
Yes, a good point. But weren't these American Indians mostly hunter-gatherers? I don't know if you can say that they engaged in agriculture. Some other tribes did, but those didn't rely on nuts or acorns.
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