This is the ID tag that I found in my father-in-law's coin collection and was the inspiration for the journey to the creation of My Dear Emma. 

Civil War ID tags were the precursor to the dog tags of today's military. 

Imagine that you are a Civil War soldier, going off to battle, never knowing if you will return to your loved one.  Many died on the battle field and were buried there, many more were buried in cemeteries but left unidentified unless some form of identification was found on their bodies.  Many soldiers sewed their named onto their uniforms, others wrote their names on scraps of paper and pinned them to their uniform coats. Some sutlers sold embossed disks with the soldier's names on them.  The small hole would be used to hang the tag on a string or a chain so that it could be worn around the neck. 

It is unknown how this particular disk came to be in my father-in-laws coin collection.  No one in the family ever mentioned it until I came across the disk and began to research.