I met a forester a few years ago and he told me that if you took a bare, plowed farmers field, and just let it go, you would get a locust forest in central PA. This field was bare about 7 years ago, and this is what it looked this morning when i took a hike. Guy was right.
Too early for black locust blooms. That is ornamental pear. (At least it looks like it from here) Wouldn't be surprised if there are a few black locust saplings in the mix as well. If the flowers stink....it's pear.
Not pear then...pear trees won't have thorns. Might be some Hawthorns? Down where I live in Northern Kentucky the ornamental pears are all over the place.
They are of different heights, completely random, and they weren't planted as it is a property neighboring mine. I saw it grow from the field to these pictures. As far as species, I walked into the grove and got three closer ones.