Aside from the supposed black plague reference , which seems to be an urban legend, it seems there is another untruth in the actual words to Ring Around the Rosie, at least the ashes, ashes, we all fall down part.
It was my neighbor who brought it to my attention when he asked if I had any extra ashes from our wood stove. (Let's see, we're heating almost exclusively with wood. Yeah, I think I do!) Jim brought out a big bucketful and watched as he sprinkled them over his path and driveway for traction in the icy mess Mother Nature left us. Curious, Jim sprinkled some on the iciest part of our path. The results were amazing.
I did some internet searching and discovered these references to this use of wood ashes as well.
Google Book Search
Symptico at MSN (look under the section titled Be Ready For Trouble)
Mother Earth News (check in the comments)
So it seems that if we use ashes, ashes, we will not fall down! We'll also do less harm to the environment, save money and not bother our pets feet. Just remember to wipe your feet well so you don't track wood ash into your home.