Named by a tabloid in the "golden age of alliteration", Ma Mayhem and her husband ran afoul of the law and committed a series of unnamed crimes, presumably old-fashioned heists. She had two sons, Slim and Carl, whom she kept on a tight leash and disciplined with tough love. At some point, her husband ran off with another woman, leaving the gang comprised of only Ma and her sons. From that point on, Ma Mayhem refused to be reminded of how her husband left her with something, and often pretended that her husband died.
After getting out of prison, Ma Mayhem embarked on a crime spree to reclaim a set of rubies which held special meaning for her. It was the first swag she and her husband had stolen together, and had promised never to fence it. She retrieved a ring from a billionaire's mansion, a pair of earrings from a state building, and finally a necklace from the Museum of Fashion. In the museum, she was intercepted by Batman. A battle ensued, and the trio overmatched the Tomorrow Knight. Ma and her boys fled, but unbeknownst to her, they were carrying Terry's Eggbaby, which he used to track them down.
As soon as Batman went to his Eggbaby's rescue, Ma Mayhem grabbed the loot and made a run for it. Batman set off in their pursuit across the city, while Ma tried to shake him off. Atop a building, Ma took on the Batman, after he had subdued her sons. She swung at him with her purse, which Batman cut off, causing it to fall over the building. Without thinking twice, Ma plunged off in pursuit of her precious stones. Batman snared Ma Mayhem in a grapple, saving her from certain death, and presumably returned her to jail.
Powers and abilities
Ma Mayhem didn't possess any special abilities or weaponry, but she was considerably strong, and was able to tackle Batman on two occasions.
Ma Mayhem bears a striking resemblance to 1930's figure Kate "Ma" Barker, who was popularly depicted as a gang leader who went on violent crime sprees with her sons (though history has since showed that the Ma Barker image was primarily a myth). Voice actress Kathleen Freeman had previously played a similar character, Muriel Dillon, in the film The Naked Gun 33 1/3: The Final Insult.
Ma Mayhem and her sons also appeared in Batman Beyond #19, "Royal Mayhem", where they kidnap Princess Vinishri of Uganistan.