I'm sure I couldn't tell you exactly which Rudbeckia it is you're seeing, but my guess is that it is probably R. hirta, R. laciniata, or possibly R. triloba. R. hirta seems to be fairly common.

I was passing through Newcastle yesterday afternoon and saw large stands of Helianthus, Solidago, and Rudbeckia (sunflowers, goldenrod, and blackeyed susans). I could have collected seeds there and created my sunflower border for free! Shucks...

Here is the USDA Plants profile page for R. hirta, you can check out the pics for the other species there too...

Here is a link that might be useful: Rudbeckia

The other possibility is that it's a Bidens (tickseed) of whatever sort - probably B. aristosa. The stems are slimmer, and there isn't a real heavy center (though you wouldn't know it if you happen to run afoul of the mature seeds, or have to pick them out of a pet's fur!). These are much more common in mass along the roadside than the Helianthus or Rudbeckia (at least in fall), and present a very different picture from the goldenrod.

http://www.loudounwildlife.org/HHFallWildflowers.htm

I don't think there will be a lot of difference, at least in genera, between Northern VA and where you are, based on what I've seen driving.

Robin

Here is a link that might be useful: Bidens aristosa

Around my area the "yellow ditch flowers" are the Bidens ... they seem to spring up from nowhere about now, don't they? We love'em.

Thanks for all the help. Yes, I think they are Bidens. Some have a darker and larger "eye" like black or brown eyed susans but most appear to be tickseed. All of them are beautiful and so cheerful this time of year.

With no photo to go by I can only bring to mind a lovely yellow plant I found growing alongside the road near Bedford, Va. It's a yellow aster. Grows to about 4 ft tall in my garden (much like New England aster) Does great in my now garden here in Connecticut. Margie (former loghomelady)

Is that the one that looks like a yellow cosmos? We had one pop up in a bed next to the house this year and it is beautiful but afraid it might be tickseed and with three dogs that is all we need.