From personal experience, in Virginia and the pacific northwest, you get plenty of berry roads. Roads literally lined with prolific blackberry bushes and sometimes raspberry bushes too. Seriously, these things are weeds. Especially raspberries. They're fucking delicious weeds. During season, plenty of folks park on the side of the road to pick berries. These road berries are better by magnitudes compared to store bought ones.

I have yet to see salad roads, but would love to see it. Diversity is "weed" edibles would be awesome.

Depending on the traffic loads of the roads i'd be wary of eating them for 'organic' reasons. The same goes for the embankments of railroads which are sprayed with herbicides, at least where i am.