According to the trusty dictionary, ragamuffin means:
n. a person in ragged, dirty clothes.
Whilst, according to Brewer's Dictionary of Phrase and Fable....
A muffin is a poor thing of a creature, a "regular muff"; so that a ragamuffin is a sorry creature in rags.
The Concise Oxford Dictionary of English Etymology describes the word "ragamuffin" as coming from the word "rag" meaning a scrap of textile material. Throughout the 13th Century the word "ragged" was used to refer to the devil, in the sense of looking "ragged" or "shaggy" in appearance.
However, it is also a breed of cat, that apparently (as Wikipedia tells me) appeared in 1994.
In literature, popular children's author Enid Blyton wrote a novel called The Ragmuffin Mystery that was the last book in her Barney Mysteries series, and was released back in 1959. Caribbean Sci Fi writer tobia S. Buckell also released a book called Ragamuffin in 2007.