Mystery Plant Identified

After getting two suggestions, and carefully perusing the available on-line diagrams, I've concluded that my mystery flower of the other day is Cota tinctoria, known as Golden Marguerite or Yellow Chamomile.  Thanks also to those who suggested Lasthenia Californica or California Goldfields.

Here's the flower again.  The challenge is that there are many such yellow daisy-like flowers, so it's hard to tell by the flower.

It was these two diagrams that I found on-line that convinced me.  The leaves above match my mystery plant exactly, while those below don't.  That above is the Golden Marguerite, while the illustration below is the California Goldfields.

Compare the leaves of the actual plant here, and I think you'll agree with me.  It was actually the Head Gardener here who sorted it out, and vaguely remembered tossing some seed in that area.  I guess the seed successfully germinated!