I recently purchased some rural property in eastern Kansas and this is the first weed I need identification on because there is just so much of it! It is growing by a creek in sun, not in the woods.
Since I have no idea what famiily it's in, I don't know where to start when it comes to ID-ing things on the internet. Any good sites?
Here is a link that might be useful: http://www.flickr.com/photos/51503848@N00/3833824241/