Beggar Ticks, Bidens frondosa, is another success story in the use of Newcomb's Wildflower Guide. With those leaflets, for a moment I thought I had a cannabis variant!
When I was a kid, I knew this plant by its barbed achenes that would stick to my green sweater. Back then I called them sticky birds (see comments below for the real story!). As the season progresses, I'll try to pick up some photos.
From Popular Science:
"It is strange how an interest is suddenly awakened about the most commonplace objects in life. We move for years among old, familiar things without giving them a passing thought, when all at once some subtle spell is cast about them, and they become vested with a charming interest. I have tramped many times though autumn woods and picked off the "stickers" with no good will, but today they strike me as more than "stickers". I have discovered an old friend among them."
Trotter, Spencer. Burs and Beggar's Ticks. Popular Science. Nov 1897. 68-9. Web. Google Book Search.