Pholistoma membranaceum
Boraginaceae (formerly Hydrophyllaceae)
I was confused when trying to ID this flower, because the leaves looked like fiesta flower, but I thought fiesta flowers were bluish. Same genus, different species.
Fremont's star-lilyI'm not positive about this ID to species. It's apparently related to the soap plant.
ps 03/10/11 & edited 07/26/11 - I'm positive about this ID, because the stamens are less than 1/2 the perianth. I've also updated the names and links.
California saxifrage