Not necessarily, porkpal. It could be rosier de macartney, as you suggest. Right off the top of my head, I can think of the following possibilities. It could be the exotic invasive multiflora rose, the bane of farmers and landowners here and, I think, probably in Alabama. It could be rosa carolina, aka the Pasture rose, one I've seen here growing along roads, or maybe rosa virginiana.. It could also be rosa palustris aka swamp rose or it could be rosa setigera. It could even be an old rose that was once in cultivation, planted by someone now long gone.
Clockwork, without a picture or even a description we can't narrow it down any better than that. Also, it would help to narrow it down a little if you could tell us where you found your rose in Alabama. Northeast? Southwest? Central?