Valuable lessons in your post. Thank you for sharing. I think a lot of people sometimes forget about these basic rules. People will source wild herbs from vacant lots without asking first "what was the growing conditions". At first, this might not be a big risk, but when ingesting a lot over time the potential risk of getting sick might not outweigh the potential good.

And I particularly like the tip about not taking too much. We are after all part of a bigger eco system! Taking just enough so that (i) animals can also still eat some and (ii) so that there can be enough for the next year as well (i.e. so that the plant can reproduce).