That's funny, I was just thinking we needed a resource
thread for people looking to ID plants here on permies! Well done!
I would say to anyone who is planning to post pictures of an unknown plant, there are a few things that really really help us to come up with an answer for you. First off, of
course, is good photos, and I'd suggest at least two or three. One of the whole plant, so we can see the growth habit. One close up, with attention to leaf shape and how the leaves are attached to stems. One of the flowers fully in bloom - and this really is the best way to identify any plant, and differences in flowers are how most of the field guide
books are laid out. If you post something before or after flowering and we don't come up with an answer, come back to the thread and post a picture of the flower later - it could be just what we need for an ID.
Also, knowing where you are located is pretty key, as well as the conditions where the plant is growing - woods, fields, roadside, etc?