I found this growing down my street underneath some mailboxes. I think
the city planted it.

http://ingsoc.crappyhosting.com/unid_flower

They planted it underneath the mailboxes last year so that it filled
the space, about 6 feet by 2 feet. They pulled it out at the end of
last season. This year they planted geraniums and day lilies. However,
it's growing back from last year. I am unsure if this is due to
re-seeding or if it's regrowing from old roots. It is actually even
growing out of some of the cracks in the surrounding pavement.

As you can see from the pics, the flowers look poppy-like and are in
shades of white, orange, yellow, and red. There are no leaves; the
foliage is soft with thick, fleshy spines, like anemone.

So far no luck in trying to find out what this is. All the poppy pics
I've looked at have flat "regular" leaves.