Opal plums, the first of European plums (along with July Green Gage) to ripen. Flavor is mild but very pleasant.
Catherine Bunnell plums (a Luther Burbank selection, has been considered a lost variety for a while). A nice early Asian plum, flavor is a bit reminiscent of Santa Rosa, but the fruit size is smaller.
A Howard Miracle plum tree, I expect these plums to start ripening in a couple of weeks. One of the best, if not the best, of Asian plums flavor wise. They continue ripening from late June to mid-late September.