This weed is plentiful around the Syracuse NY area, where I live. The leaves appear in late spring and are sort of lance or arrowhead shaped.
The flowers appear around June and July. They are quite pretty. Each stem is about 20" tall and has small bell shaped blue flowers with 5 small petals. It travels by underground roots. When you pull it, you think you have the root, but you don't. The largest part of the root goes quite a bit deeper.
People seem to like it and I see it growing in gardens by permission, but I don't like it - it can become quite a nuisance.
Here is a picture of the flower.