This is a Pink-margined Monkeyflower, a species that looks like hasn't yet made it into the iNaturalist database. Found yesterday by a field trip participant while we were leading a butterfly trip to the Horse Mountain area. This species was just discovered in 2013 and did not make it into the recentmost revision of the Jepson Manual. It is only known from a few locations in Humboldt, Trinity and Siskiyou Counties. More info here: https://www.fs.usda.gov/detailfull/srnf/home/?cid=STELPRD3815551&width=full