On Wed, 16 Jun 2004 21:38:48 GMT, Scott Ranger wrote:

I agree with PvR and Monique that it's in the Brassicaceae (Cruciferae) and
will hazard a guess that it's in the genus Arabis, the rock cresses.
Scott

Arabis Glabra (Tower Mustard) looks like a good bet to me. The various
online photos match quite well, and it appears in plant lists for the San
Juan Islands. I'll try to catch it flowering next year!