This plant grew from a piece of cardboard containing tomato seeds. I let it grow out of curiosity, but still have not been able to identify it. Note the hairs on stem like tomatoes, and the thorns on the under side of the leaf stalks. Please help. Thanks so much.
Hampden County Massachusetts
Your mystery plant is cleome, Cleome haasleriana, an old-fashioned annual which often self-sows generously. Bees often visit them.
Yes! That's it! Thank you so much! :)