It could be a Cardamine species but I don't know which ones you might get in your area. Where I live it would be Cardamine pratensis which I believe has naturalised in N America. For future reference it is best to include the leaves in pictures. They are often the deciding factor in an id. Also there is no indication of scale in the photo so I might be completely misinterpreting the size of those flowers. This post was edited by floral_uk on Fri, May 16, 14 at 15:14

Thank you for the response! I did figure it out as well, once I realized that the flower closes up in the cold, and found a few similar shots. But thanks again...

I happen to like Digitalis grandiflora which is a true perennial while many other Digitalis species are not. For example, Digitalis purpurea is biennial. The flower color of Digitalis grandiflora blends with any color. It's a great plant and you will find it in many of the finest gardens.

The deeply cleft petals reminds me of one of the Epilobium sp. (Fireweed). CalPhotos should have photos of all the native ones. Check the link for the Sierra species. Rb Here is a link that might be useful: Epilobium obcordata