There's a hole in my yard

Yesterday evening, I was alerted to the squawking and clicking of ravens in the front yard. They appeared to be strutting with round white objects in their beaks, and since we don't have ping-pong balls in the yard, I thought, "Oh, they're eating toadstools." (It's rained A LOT this spring.) Then I realized the grass was cut recently-- making for a less hospitable environment for the fungus. I went out to investigate and found a hole in the lawn. 

We've lived in this house for fourteen years,...