Miner's lettuce

"A very early-blooming fleshy annual of damp shady places in coastal sage scrub and oak woodland. The small flowers can be white or pinkish. It is distinguished by the deltoid shape of the lower leaves which turn red as the plant dries out in the summer heat. It was enjoyed raw or boiled by indigenous peoples, and used by California Gold Rush miners as a source of Vitamin C to prevent scurvy."
http://nathistoc.bio.uci.edu/plants/Montiaceae/Claytonia%20perfoliata.h…