Psoralea pinnata
AKA "Blue Pea Shrub" or "Grape Kool-Aid Tree"
Psoralea pinnata got its silly nickname from the scent of its pea-shaped blossoms (springtime).
This is a small tree or large shrub, and mostly that seems to depend on how it is pruned. Most of the year it is handsome but unremarkable, but in the spring it explodes with little blue flowers that have a sweet, fake grape flavour scent. You might think that could be really awful, but somehow it avoids the potential badness of an entire yard smelling like a kindergarten snack hour.
This specimen is growing at the Leaning Pine Arboretum at Cal Poly, photographed Spring 2006.
I collected seed to start this on my own, then I discovered seedlings at Annie's Annuals in June 2006. So I bought one, because it shaved a year off the planting schedule.