No need to reinvent the wheel. The predominant source of calories for most people for most of human history has been: Acorns. Oaks grow throughout the temperate zones, and produce storable starch by the ton. They require processing before they're edible, though, and there's a lot of ignorance and misinformation on the internet and in print about it. (I think Samuel Thayer is the best authority. His book Nature's Garden devotes a full chapter to it.)
And to continue the tangent this thread has gone off on, because it's important: Animals eating a plant emphatically does not imply that it's edible for humans. Squirrels will eat Amanita mushrooms that are deadly to us. Birds will eat stones. Deer will eat acorns, hellebore, skunk cabbage, loco weed, deadly nightshade, poke and woody browse, all of which are toxic to humans, at least without significant processing. Take a little bite of raw skunk cabbage and see for yourself. It won't kill you, but it'll feel like a mouthful of bees, and it'll sure convince you that we have a different physiology.