Id Tags in White or Gold Brass
In the outset of the war after Manassas and the mass carnage of the bodies left behind soldiers were afraid of not being identified after their death for the families to retrieve their bodies. Soldiers then started to use cardboard labels with their name, rank and company on to identify them. Later in the war advertisement started to appear in newspapers for solid discs so you could engrave your name on, also jewellers made id discs from coins which is where the first dog tags took their place in history.
Here is a reproduction ID tag in design of a coin which would have been a private purchase from a Jeweller