In my past I used to hunt butterflies. Some of my old skills and instincts still kick in when a butterfly flutters by. I did not do very well getting a picture of this Anthocharis sara Pacific orangetip (see http://www.butterfliesandmoths.org/species/Anthocharis-sara).
Anthocharis sara Pacific orangetip
I failed to get a picture of the orangetip on a flower, but it was on this flower that appears to be a brassicaceae (I am pushing my plant skills):
Down the slope I came across a flower I did recognize, but not the same as the above:
Brassica rapa is a prevalent spring flower of California; however, it is not native in North America, but is now firmly established. It is listed as a noxious weed on some lists. The NRCS does not have it in Jefferson County where I saw it, but someone working on removing noxious weeds at the base of the slope was including it in weeds to be pulled along with poison hemlock.