California poppy grows in different regions of Western United States, east to Texas, and north to the state of Washington. California adopted it as a state flower in early 1900's.
Early in spring, gentle California hills are covered with this rich, beautiful golden bloom. Of course it depends on the amount, and timing of the rain. Too little rain will stunt the growth, and very few plants will bloom.
But in a good year, it absolutely takes your breath away if you happen to visit Antelope Valley Reserve, or any other area where poppies thrive.