Par, my collies never rolled in much either besides just rolling on the grass because it felt good, but they weren't rolling in a scent (it's easy to tell the difference). Willie used to love to rub up against cedar trees though. Tasha is my biggest roller, she loves rolling in anything with a strong scent, whether it be a fresh basket of laundry, pine needles, mowed grass clippings, or something dead/rotten . Tommy seems to mostly roll in icky stuff.

Unfortunately in the spring, because we have so many fir trees surrounding the yard and thus MANY birds nesting all around the yard, we frequently find baby bird bodies about the yard from young ones that don't make it or fall out of the nest too early. I always hope I find them before the dogs do, but the other day they found one before I did and rolled in it. I had to give an impromptu bath while struggling not to breathe and gag.