AKA The Mercury Dime.
The 1916 D mintage Mercury Dime is the crown jewel to collectors of the Mercurys
The price goes up yearly so if you have old Mercurys check them out as you may have a valuble coin.
My Mother gave me one three years ago that i put on ebay and sold for $900. it wasnt in the best of shape so just imagine what a fine condition speciman may go for.
I have never found one YET metal detecting but i do have a lower mintage of a different year in very good condition that i dug up and is worth around $200
Look thru your old coins, you just might get surprised?