What plant might this be?
It could be an elm, but we can' be sure from the photos. Elm leaves are distinctive for being uneven at the base of the leaf--sort of lop-sided. Look at some photos online. A few of the leaves suggest this trait, but not all. If leaves haven't all fallen yet, you should be able to see this on the tree yourself.
You may want to send us some more photos later next year. Include fall color and a ruler or something to help us gauge the size of the leaf. It's probably too immature to bloom and produce seed yet, but that is going to be a certain identifier.
There are native and invasive elms so it's worthwhile to pursue this.