That's what I've been thinking since I first saw it, then I stumbled over a photo of a young nyssa sylvatica someone was selling and it looked awfully much like what I had.
I don't know of any southern magnolias very near my garden (our lots are 1.3 acres or larger), but my neighbor on one side has a lot of huge gum trees.
If there's a chance it's a magnolia, I'm keeping it but if it's a gum tree, definitely not.
Thanks.