Hey, crooketarrow, hillbilly61. Nope, the one tree I'm sure it's not is sweetgum. I know sweetgum (and those darned annoying balls that come with it). I actually questioned several times if this could be sweetgum, but I would have noticed a sweetgum in the front yard long ago I'd imagine. Good suggestion though.
Unless... the saplings don't produce the balls? That would make a difference. Ugh, now I'm questioning it again.
Thanks for all the responses.