Ask anyone on the street what Lizzie Borden did, and they'll probably recite the rhyme:
Lizzie Borden took an axe
gave her mother forty whacks
when she saw what she had done
gave her father forty-one
In 1892, Lizzie Borden's parents were found hacked to death in their home. The rhyme fudges details a bit, as one might expect: the murders were committed with a hatched, neither received quite that many whacks, and Borden herself may not have done it at all! In fact, the jury acquitted her in about an hour and a half. No murder weapon was found. But historians remain divided over whether she was really the killer or not to this day. The "real" killer was never found. See the wiki for more
As to the rhyme itself, it's sometimes said that it was written by a newspaperman at the time of the 1893 trial. I can't find the rhyme in any paper from before the 1920s, or in print at all before 1907, but I wouldn't doubt that it's from the trial era. Some also say that Theodore Roosevelt got a real kick out of the rhyme, though no one seems to have a good source on that (besides the fact that he appointed William Moody, one of the prosecutors in the trial, to the office of Attorney General).