Here's a true story, of something on a smaller scale : I talked to a fellow, who was in his 50s age-wise, about 20 years ago. He was a maintenance worker at a state park here in CA. This park is historically themed, has historical exhibits and significance (the name of the park/monument shall remain anonymous) . There is some decorative gardens in this park, that have to be plowed/ rototilled on occasion, for weed-control, grass-cutting, or whatever.
The guy told me that back in the 1970s, when he was just a college student, he had a summer job working that garden (running the rototiller plow thing in the gardens there). And he eyeballed something gold and shiny. He got off his tractor, picked it up, and it was a $5 gold piece dated from the 1850s !
He rushed to give it to his supervisor. Who looked at it, and said that he would take it to the park's dept. staff archie for examination. This student worker went back to his job. Later, when he attempted to ask his supervisors what had ever become of the coin, he got no answers. Other than vague things about "It's still being studied", or "we passed it on to so & so", or ... just basically the "mind your own business" type of answers.
The more this student worker thought about it, the more he wished he'd just stuck it in his pocket. To this day, 40 or 50 yrs. later, he's never seen it again. It's not in any of the museums associated with this state park, etc... He figures that some head ranger simply now has a $5 gold in his personal collection, or that it's long gone on Ebay.