A ring is currently a useless item, and often considered as junk.
A ring is a jewelry item and has no use, being added purely for the purpose of clutter, creating more realism for the player when looting.
Rings can be found on corpses, in purses and in some stores.
From newitems.txt (Project Zomboid directory/media/scripts/)
Weight = 0.1,
Type = Normal,
DisplayName = Ring,
Icon = Ring,
MetalValue = 15,