I've seen Chinese Chestnut before, there's actually a lot of them where I run, but I don't believe I've seen a hybrid before and this could be one, but due to its size and leaf characteristics, I'm fairly confident it's American. This is a good idea! Maybe I will report it. I had a friend years ago that found a much larger one and did report it. PSU came down and tested it and did determine it was pure American, growing from an old root system!