In the old days here, the barns were always built facing so that the wind would blow through them when both of the doors were open. Then they would thresh the grain, and throw it up in the air. The chaff, being lighter, would be blown outside by the wind, while the grain itself would fall back down inside the barn. Perhaps you could accomplish something similar with a small amount by dropping it from some height onto a tarp while the breeze is kicked up, after beating it with a stick or something.

Nowadays we just use a combine, though. ;)

Even if you don't eat much grain, I bet you could make beer with it. Mmmmm, beer. :D I am hoping to do that with some barley once I get settled into the new/old house.