The Oklahoma Natural Heritage Inventory lists quite a few species of Prunus native to OK. You could Google them and compare fruit to yours: http://www.oknaturalheritage.ou.edu/content/biodiversity-info/plants/woody_plants/

Thank you everyone. With the genus I googled and found a picture like mine and I saw "sweetshrub". That's what it was called when I bought it at Bordine's Nursery in 2005. I couldn't remember the name at all. It has been really happy since the neighbor had the huge old silver maple taken out that was shading it. Now it just gets some shade (a lot less) and it's doubled in size and has lots of brown blooms this year.

It's okay to hard prune it. I've cut several down to stubs and they roared right back. They are invasive in the mid Atlantic, so I cut down the big ones which came with our current home. Now they are kept at six feet tall so I can easily dead head.

in our MI ... mid march might still be snow time ... so i wouldnt be surprised if we are not a bit later ... if its a bitter winter ... keep in mind.. its not air temps ... its soil temps which are usually the trigger for spring growth ... and we are subject to ground freeze in parts of our MI ... so you MIGHT be a few weeks behind beng ... ken