Big Giant Hole in the Yard

The other day, it was very nice here in Nebraska.  John went outside to shoot some hoops and mess around.  He came back in rather quickly and asked,  "Hey Mom.  Why is there a big, giant hole in the yard?"  Thinking he was exaggerating I said.  "Oh, come on.  There is not a big giant hole in the yard."  John replied "No.  Really Mom.  There is a big giant hole in the yard."

So I went outside.

OMG.  There is a big giant hole in the yard.

It is about 3 feet deep, and is in a spot in the middle of the yard that has been regularly driven over by heavy farm equipment.  Weird spot for a sink hole.  John is convinced that a meteor struck.  I don't think so, John.

Anyway, I just wanted to ask some of my older cousins, if you read this, do you ever remember seeing anything in the middle of the yard on the way back to the barn and grainery that might have caused this hole?