The "Bizarre Bits" exhibit, which ended March 27, was intended to showcase some of the society's more "unexpected" pieces.
"We get loads of just strange things that are always fun and interesting and sometimes, well, they'll stop you in your tracks."
Among them, an image of Robert E. Lee on his horse Traveller carved out of tree fungus and a wreath made from the hair from more than 100 humans. But Shephard's favorite find was a 1850s love letter from a naval officer to his wife, which contained fingernail and toenail clippings.
"He says in the letter that he kissed them before he put them in there because they'd be the first thing to touch her lips," Shepard said. "Clearly he'd been out on the water a long time."
CDC officials told Shepard they'd return the scab, which has been irradiated to kill any remnants of life, as soon as possible.
"It's been a very positive experience for everyone involved," Shepard said. "You never can tell what kind of research can be motivated by what's in your collection. That happens all the time here."
ABC News' Karin Halperin contributed to this story.