Thanks everyone. I was fortunate to be able to shoot two sunsets and one sunrise at this location a couple days ago. The wildflower display was intense and the air was thick with the perfume of the sand verbena (purple flowers on the left).
The crater is a volcanic cone which may have been active as recently as 600-900 years ago. A fun story is that one of the local high schools (50-60 miles away) in the 1950-60s, started a tire fire in the center of the crater during a party. The fire lasted for days and the black smoke could be seen for miles around. Folks driving by thought the volcano was going to errupt and notified the newpapers in Los Angeles- which started a panic of sorts, at least until geologists flew over to investigate.