I recently picked up a small lot of three WWI dogtags from a medical officer named Liva C. McLain, and found that he likely served as a surgeon with the 7th Evacuation Hospital at Chateau Montanglaust in France, a hospital especially equipped to deal with those wounded with mustard gas.
Liva C. McLain was born in 1901 in Bakersfield, CA and died in 1971 in NY. He is mentioned on page six of the following medical corps pamphlet,
http://jama.ama-assn.org/content/LXIX/25/2121.full.pdf
It looks like Liva served with the hospital during some key battles during the war. His hospital served the wounded at both Chateau Thierry and Belleau Woods. Here’s a good JSTOR article about the unit’s participation at Belleau Woods:
Here is a link to a soldier in the 103rd Infantry Regiment of the 26th Division who spent some time recuperating at the 7th Hospital:
The 7th Evacuation Hospital was organized on 26 November 1917, at Fort Riley, Kansas, as Evacuation Hospital Number 7. The organization participated im WW 1 in the following campaigns: Champagne-Marne, Aisne-Marne, St Mihiel, and Meuse-Argonne. It received a decoration streamer with colors of the French Croix de Guerre with Silver Star, embroidered St Mihiel-Msuse-Argonne. The organization was demobilized on 1 May 1919


You mention 3 tags, but only show the obverse & reverse of one here. I assume 2 are identical as shown above, which would have been worn around the neck on a cord similar to shoestring. If the third is an oval-shaped tag with a small chain attached, that would have actually been a wrist ID bracelet worn on the left hand. This was to maximize the opportunity to identify the body even if it was badly mutilated.
Thanks for the info! The other two are identical, so I didn’t take the time to scan them.