Blue mistflower (Conoclinium coelestinum) is blooming now in southwestern Pennsylvania.
At this close range you can see it’s related to Boneset, White Snakeroot and Joe-Pye Weed, all of which used to share the genus name Eupatorium.
(photo from Wikimedia Commons)
I remember seeing this growing along the Youghiogheny River near Cedar Creek County Park. I was quite taken by the blue flowers. Since then, I have seen it in cow pastures in Greene County where is seems to prefer moist places, but not always.