Nodding Thistle aka Musk Thistle (Carduus nutans) 2015-5-10 Patuxent Research Refuge, Anne Arundel County, Laurel, MD

https://www.minnesotawildflowers.info/flower/nodding-thistle
Leaves are stalkless, mostly hairless except for the main veins on the underside, and may have a white cast on the edges, especially early growth rosettes. Leaf bases extend down the stem, forming spiny “wings”. Stems are many branched.
-flower head inset, with permission, by Bernd Haynold

http://www.wildflowers-and-weeds.com/weedsinfo/Carduus_nutans.htm