When I took these pictures, I thought I knew what this was, but after spending some time on-line trying to verify, I lost confidence. So I'm asking y'all. My guess is bull thistle, Cirsium vulgare, though this plant doesn't seem to have long terminal spines like C. vulgare does.
It probably doesn't matter; these pictures were taken 13 May, and the plant's probably been cut down by now, but I thought it had a sort of admirably dense and pointy form, the sort of thing people would try to grow on purpose if it were more difficult to grow on purpose. (If I'm right about the ID -- hey, it attracts butterflies! It provides food for songbirds! Pest-resistant! Hardy! Brightly-colored flowers! What more do you want?) It at least looks like something I'd try to grow indoors, if I thought that were possible. Luckily for us all, I don't think it's possible.
Anyway. If anyone can confirm, or suggest an alternate ID, I'd appreciate it.