Q: I have a single hole in my front lawn, about a foot deep, cleanly dug without loose dirt around it. It’s kind of in the middle of the lawn and not near anything.
A: It looks like a spot where once lived a small tree whose stump was covered with soil when your house was built. The grass held the soil together for a while but recent rain made the soil heavy…… so it caved in.
Shine a light down into it and see if you spot any remaining bark. You might also see a small tunnel near the bottom where a major root once grew.