nickelsnbills said:

Maybe a hackberry tree?

Its a tree. I want to say Mulberry but the growth habit is exactly like my baby Ume' trees which are Prunus.

I'm not sure what it is, but we have lots of mulberry and hackberry sprouts in our yard, and it isn't one of those. The leaves to look hackberry-shaped, but young saplings hold them differently, more drooping sort of? hard to explain.

Lots of possibilities for trees and bushes with simple serrated leaves unfortunately.