I found this planted tree at a park in Eastern PA. It looks like a birch to me but the bark is curious. Is it a yellow birch (which I've never seen planted)?
Not a Birch (Betula sp.) at all, but rather - I think - a species of Cherry (Prunus sp.).
I should have thought of that. I figure I know all the cherries so well that I didn't even consider it. lol.
Prunus serrula can have lustrous and exfoliating bark like that.