Solidago, Eupatorium, come readily to mind, taller, free-seeding late bloomers.

Definitely not golden rod. Or Joe Pye Weed but I wish it was! I've tried wintersowing that for two years with no luck.

Look up Horseweed, Conyza canadensis and Pilewort, Erechtites hieracifolia.

http://www.missouriplants.com/Whitealt/Erechtites_hieracifolia_page.html

http://en.wikipedia.org/wiki/File:Canadese_fijnstraal_plant_Conyza_canadensis.jpg

Or just post an image or two

This one is about 3 feet tall.

a smaller one still in the ground.

At times there is purplish coloration but not most of the time.

Also, I pulled about hundreds of them out of about 120 feet of green beans last night. I somewhat enjoy weeding but I do have other things that need doing:)

Compare your plant to Amaranthus viridus, Slender Amaranth.

Showed my FIL this weed last night and he says water hemp and some it might be pig weed. There seem to be two very similar plants. One is only a medium green like the first picture while the others have a lot of purple like the second picture. I just haven't found a photo of pig weed yet that 100% convinces me that the purple stuff is pigweed. Perhaps water hemp can have the different colorations?

Definately Amaranth. Known by the moniker 'Red Root' around here. We also have Spiny Redroot, which looks almost the same, but has a nice sharp spine hiding underneath the leaf to remind you it doesn't want to be pulled.

Water Hemp and Pig Weed are both members of the Amaranth family of plants. Some people around here grow them as a cover/green manure crop.

I was unable to tend to my garden for two summers. Of course it was overcome with weeds and I spent a whole summer getting it back to where it was manageable. I found that where pigweed had taken over, it had so improved the hard clay soil that it made a huge difference in the structure of the soil and now several years later the difference can still be seen.