SPINY POPPY (Argemone gracilenta)
This plant may reach up to 3 feet tall, producing wide, bright-white flowers with 4-6 thin petals and many yellow stamens. The flowers are very attractive to pollinators (see the native bee on one petal in the image below). (Click on the image below to enlarge it.)
Below left, an image of the basal leaves -- all the leaves are deeply lobed and up to 8" long, and both leaves and stems are spiny. But there is lots of action at the flower-tops -- not only the pollinators find it attractive, but also the camouflaged white spiders who lurk in and around the white petals, as seen on the image at right: (Click on each image to enlarge it)
This plant, by the way, is poisonous.