A natural stone with a hole in the center and gift from the earth to the lucky finder.
A totally throw away .. cannon fodder ..shove it in the mouth of the monster and run for it type of character. Useful though for ‘taken with a pound of salt’ information and running small unsavory errands.
In one region of a forest, all of the trees are identical, down to the leaves and the twigs. If the PCs carve something into one of the trees, it could mystically propigate until it covered all of the trees, or could vanish since it was not carved into the one true tree.