Although a very common plant, this is actually a European import, not a native. The darker green, non-blooming plant in this picture is either Ironweed or Joe-pye Weed; I always mix them up until they bloom in late summer.
The square stem marks it as a member of the mint family. It is either Narrow-leaved (aka Slender) Pycnanthemum tenuifolium or Virginia (P. virginianum), I'm not sure which. Even my botanical guru, Jim McCormac, can't tell from this photo.
Host plant for Monarch butterfly caterpillars.
This is a good hummingbird flower.
Watch this one - it is a common weed in many crop fields, and I have had bags of black-oil sunflower seeds contaminated with bindweed seeds. If you get a bad bag of seeds, bindweed can infest your yard and be hard to eliminate.