Welcome Scott. There are not very many of these shells, but I can tell you a story of the recovery of two of them.
The history of the Sullivan’s island has been dominated by Fort Moultrie, which, until its closure in the late 1940s, served as the base of command for the defense of Charleston. Many of the quarters subsequently reverted to civilian use and more were torn down and replaced with beachfront mansions. Sullivan’s Island is a very affluent suburb of Charleston.
One day a woman who lived in one of these homes was working in her yard at the end of her driveway and uncovered a shell buried in the sandy soil. She called the authorities.
Turns out she had discovered a 300pdr Parrott shell that had marked the driveway end and been placed there back in the military base days. The official who showed up figured there might be another marking the other side of the driveway and sure enough there was. He kindly obliged her and with her grateful permission hauled them away for her. I know this person, and I believe that is how the one shown in Jack Bell’s book was saved.