Definitely Black Cherry. If limbs break off (they are brittle) don't let the horses eat wilted leaves or the fruit. They develop a toxin that is harmful to livestock.
The seed, like other member of the Prunus gensis, contain cynaide poison in very small amounts. The inner bark as well. My grandmother made cough syrup out of the inner bark, so I think the cynaide must be in small trace amounts. We all have tiny amounts of cynaide in us anyway.
We call them wild cherrys. I have a friend with a sawmill and I got him to saw a large one into lumber for me. I made a nightstand out of it with the legs out of mountain laurel. The lumber was about the hardest I had ever worked with.