In South Carolina an African American woman, Ozella Williams, made quilts in patterns that, so her mother said, formed a code for navigating out of slavery on the Underground Railroad. The theory of the threaded language got a boost with the 1998 book Hidden in Plain Sight: A Secret Story of Quilts and the Underground Railroad. The trouble is that respectable historians of slavery, including David Blight and Paul Finkelman, can find no evidence for it.
Says Blight, who has edited an essay collection in honor of the opening of the National Underground Railroad Center in Cincinnati, "This is 'myth' of the softest kind that serves the needs of the present for people who prefer their history as lore and little else."
Finkelman says that in his extensive research of antebellum court papers and other documents, he has never come across the slightest reference to a code in quilts. To his mind the interesting question is "why people are so desperate to create" this myth.
UPDATE: Another scholar on the H-Slavery list says, if you believe the quilt story he has a lawn jockey to sell you.