The version of Ringa-Ringa Roses ryhme i knew since my childhood was:

Ringa Ringa Roses
Pocket full of Poses
“Husha Busha!”
We all fall down!

Recently i came accross a site which gave the US and UK versions of this ryhme:
US version:

Ring around the rosy
A pocketful of posies
“Ashes, Ashes”
We all fall down!

UK Version:

Ring-a-Ring o’Rosies
A Pocket full of Posies
“A-tishoo! A-tishoo!”
We all fall Down!

Dileep had once told me about the history of this ryhme. Also found somewhere in web that this  little rhyme has its origins to the time of plague in London back in the 17th century. Symptoms of plague included a rosy red rash in the shape of ring. Sweet smelling poises were put in pockets to prevent the spread of the disease, since it was believed that the disease was spread through bad smell. Ashes Ashes we all fall down refers to cremation of dead bodies. How sad :-( . The British version “A-tishoo A-tishoo” referred to sneezing which was also a symptom of plague.