Where did the children ring around the roses come from?

from the Bubonic Plague. rings used to appear on the skin of the diseased, and (if I remember correctly) the victims started out with a fever. the children made up the song. because of so many dieing in the streets, people burned the dead - causing the ashes. The last line "we all fall down" is refering to the fact that they will most likely die soon - or they will eventually. the posys are flowers, which like most know, are put on the graves of loved ones. but they couldn't do that because the victims were burned.