Who was the gossipy neighbor who seemed to know everything in To Kill a Mockingbird?
In Harper Lee's novel To Kill A Mockingbird, it is Stephanie Crawford who provides most of the gossip about Boo Radley. Boo Radley is a mysterious character that Jem, Scout, and Dill discuss at length and have built up in their minds as a scary, shadowy, monster.
Jem gave a reasonable description of Boo: Boo was about six-and-a-half feet tall, judging from his tracks; he dined on raw squirrels and any cats he could catch, that’s why his hands were bloodstained—if you ate an animal raw, you could never wash the blood off. There was a long jagged scar that ran across his face; what teeth he had were yellow and rotten; his eyes popped, and he drooled most of the time. "Let’s try to make him come out," said Dill. “I’d like to see what he looks like." Jem said if Dill wanted to get himself killed, all he had to do was go up and knock on the front door.
Earlier in the text, readers learn that most of the information Jem and Scout have obtained about Boo Radley has come from Miss Stephanie Crawford. It was Miss Stephanie that provided the information that one day, Boo Radley had been cutting things out of the newspaper for his scrapbook when his father walked through the room. Boo drove the scissors into his father's leg, then wiped the blood off and went back to his cutting. This helps foster the idea that Boo is crazy and dangerous. She also provides the information that Mr. Radley was told to put Boo in an asylum but refused, and Boo was locked in the courthouse basement for a while. Stephanie also divulges that Mr. Radley was told he had to get him out of there or he would "die of mold from the damp."
So Jem received most of his information from Miss Stephanie Crawford, a neighborhood scold, who said she knew the whole thing. According to Miss Stephanie, Boo was sitting in the livingroom cutting some items from The Maycomb Tribune to paste in his scrapbook. His father entered the room. As Mr. Radley passed by, Boo drove the scissors into his parent’s leg, pulled them out, wiped them on his pants, and resumed his activities.
Miss Maudie is the one who puts Stephanie in her place with this comment:
"Stephanie Crawford even told me once she woke up in the middle of the night and found him looking in the window at her. I said what did you do, Stephanie, move over in the bed and make room for him? That shut her up a while." I was sure it did.
Scout's comment at the end of this quote, that she was sure it did shut Miss Stephanie up, is another revelation of her character. Her gossip only stops when someone makes it embarrassing for her to continue. Scout mentions in chapter five that no one with any sense trusts anything Miss Stephanie has to say. This is likely due to her penchant for embellishing and filling in details that are unknown to her with her own imagination.
The character you're referring to in your question is Miss Stephanie Crawford, who first appears in chapter one of Harper Lee's novel To Kill A Mockingbird. When Scout, the narrator of the novel, is describing the mysterious Boo Radley, she has this to say about Miss Stephanie:
"So Jem received most of his information from Miss Stephanie Crawford, a neighborhood scold, who said she knew the whole thing. According to Miss Stephanie, Boo was sitting in the livingroom cutting some items from The Maycomb Tribune to paste in his scrapbook. His father entered the room. As Mr. Radley passed by, Boo drove the scissors into his parent’s leg, pulled them out, wiped them on his pants, and resumed his activities."
Miss Stephanie seems to have an awful lot to say about Boo Radley, and the children take everything she says to heart. This is stated by Scout when she describes the summertime playing they initiated to act out the legends surrounding the Radleys.
"Jem would reappear as needed in the shapes of the sheriff, assorted townsfolk, and Miss Stephanie Crawford, who had more to say about the Radleys than anybody in Maycomb."
Miss Maudie has an ability to get Stephanie Crawford to stop spreading tales about the Radleys. She says:
“'Stephanie Crawford even told me once she woke up in the middle of the night and found him looking in the window at her. I said what did you do, Stephanie, move over in the bed and make room for him? That shut her up a while.' I was sure it did."
The "neighborhood scold," Miss Stephanie Crawford lived nearby the Finches and seemed to have her nose in everyone's business. If there was gossip in the neighborhood, Miss Stephanie was bound to know about it, and many of the terrible rumors about Boo Radley came from her. In fact, Miss Maudie tells the children that most of the rumors are " 'three-fourths colored folks and one-fourth Stephanie Crawford.' " We know that she is pushing 60 and is a bit overweight. When the children build their snowman, they note that it resembles Miss Stephanie. After Miss Maudie's house burned down, she relocated temporarily in Miss Stephanie's home.