In my part of the world we've been planting every corner of every field for decades now, if it can be farmed it already was/is. It's fun to watch the fellas with 16 row planters work on 2 acre fields....
Corn is king, probably 2/3 to 3/4 corn around here, my neighbor didn't plant any beans this year, all corn and alfalfa (he milks).
Soybeans are used for rotation by most.
A tiny bit of alfalfa, spring wheat, and oats is planted, but very small amounts.
I worked up an extra 1/2 acre this fall, neighbor did some tiling and that should keep it from getting his water dumped on my land. If it looks good this spring, I can work an aditional 3/4 acre in spring. Going to more corn, of course. :)