purple flowers, whorled leaves?
The ways the flowers dried off, I think it is a species of Kalmia.
Wait for others to confirm because I'm guessing on this one.
Kalmia looks close to a Rhod so I don't think it's that. Not sure what it is. I must say it's difficult to ID herbarium sample without seeing the true colours and form of the plant in natural light.
Vernonia fasciculata? Vernonia altissima? was it growing in someplace that might be damp? like a drainage ditch or a meadow?
Also known as Ironweed.
I also looked closer and the flowers are inflorescences of super tiny tubular flowers
Wis is covered with mint- grows like crazy, tho I don't know which one it is- smells good growing in the barditches tho...