Cercis occidentalis
AKA "Western Redbud"
This is a tree I would like but do not yet have. It's actually quite common in nurseries here, so I have been putting off getting one until I find just the right shape.
It's a small, slow-growing tree, to about 12 feet tall. Flowers in the spring like so:
(This is one of two of these trees near the Architecture building at Cal Poly. Photo taken March 2006.)
The blossoms are referred to as pea-like, which they are, folded over like pea flowers. The leaves are round, and come out as the flowers are dropping, right around early May. Seed pods look like pea pods.