hmm ... well, it's not Celtis laevigata. It sure looks familiar though and I think you may be on the right track with Prunus. I thought of Prunus serotina (Wild Black Cherry), the bark looks similar but not the leaves. Wild Black Cherry (Prunus serotina)
The P. serotina in my yard has wavy leaf edges:
~ I'm an old gal who still loves playing in the dirt!
~ Playing in the dirt is my therapy ... and I'm in therapy a lot!
