This plant is definitely considered to be a “weed” and many gardeners and farmers spend lots of time and money attempting its eradication. When you can identify it, provide its common and scientific names in a comment below. Also, please share any personal story you have about this plant (even if you can’t seem to remember any of its common names).
ANSWER (subsequently added to this post to facilitate the “search” function for these images): Hairy bittercress (Cardamine hirsuta)
Also, read the blog post and watch the plant portrait video for Hairy bittercress (Cardamine hirsuta).