Found these near a small watering hole that must have been used as a place to cool off etc. 1901 Indian Head penny turned into a button and a pocket watch.
Congratz on the bucket lister half-dime. All the other bucket-listers will fly past now ! And while I know that old cruddy pocket watches aren't worth anything, yet .... I always like finding those !
I would do the spit & tinfoil trick : Take a piece of tinfoil, shiny side up. Spit (or heavily lick) a spot. Put coin on it, and spit (or heavily lick) the top of the coin. Enclose it in the foil, like an envelope tight cocoon . Come back 10 minutes later, and do a gentle thumb rub (which is non abrasive and gentle, to just have human skin rub). You will notice that the black begins to come off on your thumb. Repeat as necessary.
Congrats on an awesome find, only ever found 1 myself and I swear I spent 20 minutes chasing that thing around in the hole even using a pin pointer. Amazing how small those are.