Here's an underused tree; Davidia involucrata, or Dove Tree:
It's named Davidia for Father Armand David, or Père David, a French Franciscan missionary and naturalist. He is also honored by being the namesake for Père David Deers and Chinese White Pine (Pinus armandii).
It's white, drooping "flowers" are really bracts and are in bloom in late May or early June.
The common name of Dove Tree refers to the appearance of white birds sitting on the branches, though I think I prefer the alternate common name of Handkerchief Tree.