washington state if the item is over 30 years old or has treasure trove type value --say its theirs not yours even on private land -- so if you want to lose it --tell them about it .
its really this simple ---shoot your mouth off --lose your find --
of course you all must all report your finds as "good law abiding citizens" thus clearly you wanting to enrich your state coffers rather than keep the goods found on your own lands, that you pay taxes to the state to keep control of said land. (basically the states sees your tax payments as a form of rent -to live upon the land you bought--the state of washington sees all the land and anything in it as "theirs".