He preserved more than 2,000 objects that people had swallowed or inhaled: nails and bolts, miniature binoculars, a radiator key, a child’s perfect-attendance pin, a medallion that says “Carry me for good luck.” Jackson retrieved these objects from people’s upper torsos, generally with little or no anesthesia. He was so intent on assembling his collection that he once refused to return a swallowed quarter, even when its owner threatened his life.
He was an early safety advocate for children chewing before swallowing. You can read more about his bizarre collection and interesting techniques here.
His collection will be on display at a museum in Philadelphia, and his biography has been recently written in "Swallow: Foreign Bodies, Their Ingestion, Inspiration, and the Curious Doctor Who Extracted Them" by Mary Cappello.