Puffball?

My 'Seek' app identified this as being in the class of fungi called 'Agaricomycetes' but gave me no clues beyond that. When I was a kid we used to call them 'Puffballs' but...who knows. I found this one at the DogPark with this Oak leaf inserted into it's opening. My fingers are there to show some scale. It may not be a fungi at all.  I carried it around for a bit and then left it in a 'safe' place. Be Well. :)