Here’s your week’s mystery!
This is NOT a Pawpaw. I just want to make that clear. Sorry if I have disappointed any of you.
Give me a guess!
This is an Oak Apple Gall. These galls are formed from chemical reactions given off by a wasp larvae when it chews its way into a newly forming leaf in early spring. Instead of growing properly, the leaf creates a home around the larvae that grows as it does, until June or July when the larvae changes to a wasp and chews its way out of the gall. This one obviously dropped from the tree early, possibly by a, er, squirrel biting off branches to add to his leaf nest.
Here is a website explaining more details of the life cycle of the wasp.