No cap to be a native persimmon. I dont know if the asian persimmons have a stem or cap and dont know when they drop either but I would think earlier than now. Like you said it is way late for plum and crabapples, at least the ones I familiar with.the way it looks it I thought it may be a persimmons but its a bit late for them maybe a wild plumb or crab apple only problem is its so late for all them
I would say chickenNot sure what that is but they will browse the crap out of that dewberry those things are laying in. What did it taste like?
If it is attached to a vine vs the briars, I would say it is a maypop(purple Passion flower).