This plant is all over once you learn to look for it. If well watered the fruit can be as large and tasty as the plums in the grocery stores. My go-to plants were ripped out by the Springdale Water Co. when it was cleaning growth from its ditch.
They bloom in late April. Usually seen along irrigation ditches or places where water settles. In bad years they put on no fruit. They might look like choke cherry which bloom at near the same time, but the plum blossoms are much whiter, when seen from a distance.