” ... The government will usually just confiscate finds like this ...”
A buddy of mine found a brass cannon from one of the ships that Commodore Perry burned to keep out of the hands of the Brits during the War of 1812.
He spend half a summer getting it out of the mud in Burnt Ship Creek, taking it home to his garage and cleaning 2 hundred years of caked on grime and organic stuff from it.
He just finished and was so proud of his find when the State of New York showed up and seized it without compensation.