You don't have to be a fan of California natives to recognize the Matilija Poppy (although it might help when it comes time to pronounce it – say “ma TILL a ha” and you've got it). Many instantly fall in love with its large “fried egg” flowers with petals the texture of crepe paper.
However, fair warning is necessary before you add one to your own garden. If this plant is happy, it will spread quite aggressively by underground runners, with children appearing many feet from the parent – give it room, place a root barrier around it, or be prepared to pull up unwanted babies. It is quite tall; ours reach six feet tall each year! It also goes completely deciduous in winter, so don't assume you killed it after planting it in the fall (although you do have to be extremely careful not to disturb the roots when you plant it, leaving the root ball and soil in the pot completely intact when placing it in its hole). In late fall, cut the old growth to the ground when it goes brown, and you'll get a round of fresh foliage in spring followed by more of those fried eggs in the summer.
Romneya coulteri is known as being highly drought tolerant when established, and likes full sun. That said, we've seen it grown successfully in coastal locations – even in rainy England (where they often grown it for its foliage).