Cutworms
Back in April, while planting some more rhubarb[1], I found this about an inch underground. It had evidently overwintered as a nearly-adult caterpillar
It was still dormant, and wouldn’t unroll for anything. In retrospect, I should have gotten a picture of its back, because it looks like there is a row of black dashes running along the back in this picture, but it is hard to tell for sure with only a side view.