I have lived in this house for many years. I have always had a bush behind the shed that I couldn't identify. I always knew it was green most of the year and that it had thorns but that was about it.
Well a couple of days ago I was looking at it and low and behold there was an green apple or an apple like fruit on it! I was excited but it wasn't like a normal apple. There was no stem, it was directly attached to the branch, and I have never seen an apple with thorns that are an inch or so long.
I'm not sure what it is or if it is native or a non-native ornamental plant. I live in New Albany, Indiana which is in southern Indiana near Louisville, KY. Also on my property here in town I have dogwoods, an ornamental cherry, a holly, some catalpa trees, a white pine, and some miscellaneous other bushes/hedges. It is an old property and I think most of the trees were placed here by a previous owner. My dad and I are very curious as to what it is.
Leaves are dark green and look very similar to an apple's. The fruit is very apple shaped, even has a dimple on the bottom, but like I said no stem. It is a little more round than most apples and about 2.5 to 3 inches in diameter.
See photos below, and more on flickr: