Definitely a species of Camassia aka Camas or "Wild Hyacinth" (the colloquial common name in the PNW). A mid-late spring bloomer, depending upon species to about 12 to 18 inches. Pretty hardy and trouble free. Bulbs are widely available from the major mail order bulb houses like Brent & Becky's, Van Engelen, McClure & Zimmerman and generally pretty cheap.

Here is a link that might be useful: Google Image Search Results for Camas

thanks so much for the ID, that's very helpful!