Ring Around The Rosie. This rhyme dates back to the Great Plague of London in 1665. The symptoms of bubonic plague included a rosy red ring-shaped rash, which inspired the first line. It was believed that the disease was carried by bad smells, so people frequently carried pockets full of fresh herbs, or "posies." The "ashes, ashes" line is believed to refer to the cremation of the bodies of those who died from the plague.
"Physicians that saw those with the Bubonic Plague during the Venetian Renaissance, often known as Plague Doctors, wore a bird-like mask for protection and to depict the symbol of the Plague, the raven."