I'm a little ungrateful because what with the French marigolds, corn-marigolds, and bright yellow chrysanthemums (that weren't supposed to be yellow) -- not to mention the famous yellow poppy! -- I've had an almost unrelieved spectrum of yellow/red/orange flowers this year ;-p
And yes, the California poppies will be yellow/orange too when they flower; about the only non-orange flowers I've got are the blue daisies (which, weirdly, appear to have thrown up a pink one in another pot -- maybe another bird-borne seed, like the original appearance of these flowers that I certainly didn't buy) and the cornflowers. I wonder if the fiery colours are actually some kind of indication of heat tolerance, and that all the plants that do well under these sorts of conditions tend to be this sort of colour?