Could be a purple leaved plum. It's an ornamental. The fruit are edible, just not palatable. But they are OK cooked. I've stewed them with sugar and they taste fine. Just a large ratio of pit to fruit so not really worth bothering with. Also possibly one of the red leaved crab apples. If you cut a fruit across it will either have a pit or seeds in a star shape. If you can get a more in focus picture we could tell better. This post was edited by floral_uk on Mon, May 19, 14 at 16:58

I will go with black locust as well. I took my little dog for a walk this evening specifically to look at the foliage of my Ky coffee tree and black locusts. The coffee tree's leaflets are pointed, and the locust's are not. It looks like a robinia.

That never occurred to me. But now that you pointed it out it seems obvious. I know of one oak growing about a block away. They are very uncommon here. Thank you.

When the flowers open it will be easy to tell for sure. Otherwise it looks quite like 'Montic' to me. Also this plant is one likely to be encountered at garden centers near the Pacific. I've seen some quite nice ones in shopping center landscaping in Orange County, a situation where I doubt anyone was spraying them.