Those pics are gorgeous!
Most places you're right about a few seeds not being a big deal. Where you live the seasons help contain that, as well as the more arid climate. But when you cut something like that loose in the deep South where it's warm and wet most of the time, the stuff spreads FAST. The kudzu problem down here is a great example of how quickly an invasive species can take over.
That site I linked gives you a PDF for each state and what things are most beneficial to pollinators. It's a great site.
That's a great link, thanks Hoss!