who say this quotes, but three came a day and does this quotes of boo radely come from a reliable or not ? why or why not

Scout is telling the story in the novel. Jem garnered his information from Miss Stephanie, the town gossip. Her information is unreliable.

But there came a day, barely within Jem’s memory, when Boo Radley was heard from and was seen by several people, but not by Jem.