Who is Miss Stephanie Crawford in To Kill a Mockingbird?

Miss. Stephanie was one of the Finch's neighbors and known as a neighborhood scold (nag). She also provides the children with a wealth of old stories and town gossip about Boo Radley, most of which is untrue.

So Jem received most of his information from Miss Stephanie Crawford, a neighborhood scold, who said she knew the whole thing.