Years ago, they were planted in my yard (zone 7a). The seeds are saved annually (although I don't know why since the poppies easily reseed themselves), planted in the fall, and in the spring pop up like poppies do. They have smooth solid leaves of a blue-green color like cabbage, and pink multi-petal blooms resembling shredded coleslaw. They are definitely poppies given the appearance of the seed pods, and given the manner in which they hang their heads until ready to bloom. After the internet came along, voila! - we now know they are: Bombast Rose Poppies (Papaver somniferum var. paeoniflorum).
They are essentially one of the opium poppies. (Fits well into my poison garden theme.) My advice for growing them: don't believe what you read on the internet about their cultivation. First, they should be planted in the fall and seem to prefer cool temperatures in spring - not very promising around here. Most all seeds planted in the spring turn into minuscule plants that get fried in the heat of late spring and summer.
Second, they hate to be transplanted, and never seem to recover from that shock. Third, they are anti-social plants - not liking crowded conditions. I find they seem to compete with each if close together. Fourth, they do not like heat. This last piece of advice relates to this year's crop.
In the past, a handful would grow to 3-feet tall (1 m) while others would remain midgets with almost no blooms. This year, there is the usual crop of midgets, but a few shot up to 4-feet (1.2 m) in height with gigantic blooms. The over-scaled plants began sprouting earlier than the others when weather was cooler. This may have given them a head start. When the weather changes a bit, the heat seems to toast their lower leaves, reducing the amount of food for the plant, my guess. We had a somewhat cool spring this year, so the plants with the head start really took off early while the others were affected by the heat as they began to grow.
For The Record:
Rich well-drained amended soil
Small amount of fertilizer
No serious pests/disease
Blooming: pink poppies, nicotiana, coreopsis, salvia, california poppies, tradescantia, rose, cactus