Mary Ann Cotton was convicted of, and hanged for, the lethal poisoning of her stepson Charles Edward Cotton. But it's likely that she murdered as many as 21 people, including three of her four husbands and 11 children, apparently in order to collect on their insurance policies. Local children would recite this disturbing nursery rhyme about her, “Sing, sing, oh, what can I sing? Mary Ann Cotton is tied up with string. Where, where? Up in the air, sellin’ black puddings a penny a pair.”