Hi, 

It is difficult to say at this point what it could be. It is easier and more accurate to identify plants as they mature. Bark and mature leaf arrangement, as well as any flowers and fruit can be key characteristics as well. 

This to us though, looks like a black gum sapling, or Nyssa sylvatica.

Maybe there is a mature one nearby that re-seeded or it could have been deposited from wildlife. 

Emily