WWI U.S. Army Collar Disc collection ~group 2

This is the 2nd lot of US Army Collar discs. Again, the "US" discs are quite common, and usually sell for between $5 and $10 dollars. There are different variants of the "US" disc, such as "U.S.", or "US." or "USR" (reserve troops) or "USV" (volunteer Troops) or "USNG" (National Guard Troops) or "USNA" (National Army Troops)

Photo #1 shows"
ILL. & Engineers ( Illinois home guard Engineers), US & 52nd Pioneer infantry company "A"
US & ROTC, US & RS (Recruiting Service)

Photo #2 shows:
US & Chemical Corps, US & PG2 (Prison Guard 2nd Company)
ILL & Ordinance (Illinois Home guard) , USNG & Air Corps Musician

Photo #3 shows:
USNA & Coastal Artillery
US & Air Corps

Photo #4 Shows
USNG & Signal Corps
US & MG (Machine Gun crew)