Trapping moles at a customers property and came across this in her garden/landscaping box. Something dug a hole and then backfilled it. Hole is roughly the size of a tennis ball, maybe a touch smaller. I came across this earlier this year at another property. Moles and gophers are the only thing I know to backfill their hole, but this didn't seem to have the characteristics of either one. Thanks.

Grey squirrel is my guess.

Squirrels bury there nuts so could be squirrel, they like loose soil such as that in the picture cause my grandma has squirrels digging in her flowerbeds all the time

I would also lean towards squirrel, but maybe a cat using it as a latrine.

A great place to pee?

If was here, I'd say chipmunk, don't know if you have them where you are

Chipmunk or thirteen striped ground squirrel.