My guess is Ailanthus altissima with a common name here of 'Tree of Heaven'. It's a horribly invasive pest here and I think maybe even worse in higher rainfall locales. If you are successful with the seedling and that is what it turns out to be, you will be fighting it for a long time. They sort of look like a tree version of a shrimp plant, don't you think? Someone else will chime in here, I expect, to confirm or correct my suggestion.
