I usually have the same ol' weeds returning year after year. But this is one I don't believe I've ever seen before (or maybe I have and it doesn't usually get so big because I stay on top of pulling and mulching most years). The leaves look spiky, but there are no spikes on the stem. They flower buds actually remind me a lot of rose buds. Anyone have any thoughts what it might be?

P.S. Please disregard the mess in the background. I'm still in the clean-up stages from a massive hail storm that tore our town to shreds.