Now, these are not the famous California poppy (E. californica - I always have a hard time spelling Eschscholzia correctly). The way I know is to look under the flower for a red ring. If present, then CA poppy; if not, then good luck! I already guessed these were tufted poppy, because that's just what they look like to me. I'm not familiar with the miriad of other native poppies to know any differently. Maybe the folks in the Sierras are the ones that call this foothill poppy, but I've never heard that name actually used. The tufted poppy is the one that gets everyone going gaga at Hite Cove near Yosemite.
As with the woodland star, I asked the CNPS folks 2 days later to confirm. What I thought was an easy casual question ended up pulling out loupes and keys with a debate over whether it lacked hair. Honestly, I couldn't follow the conversation, but I think they were trying to decide between tufted poppy and San Benito poppy (E. hypecoides), which is also on the latest Pinnacles plant list. It's tufted.
Ed Ross advised me once that if given the choice between two flower photographs, always pick the one that has an insect on it. He said it made it more interesting. So, there's a bonus unidentified little beetle in the first photo above. However, I'll admit I often pick pretty over practical. I do like poppies of all sorts, including the fancy garden ones. They're so cheery. I forgive our natives for being yellow.