✅ SOLVED Hat, lapel, or tie pin maybe?

[Catahoula]

Found this today at the site of a football field that was abandoned in the mid to late 1940s. There was military traveling through the area during the Civil War, but the item feels too lite to me to be of that era. I noticed after applying some water that the "shank" on the backside seems to be threaded. Also, the field is almost surrounded by old railroad tracks... If that helps at all. Any help identifying, or even guesses at this point, would be appreciated.
Thanks much.

 

[Charlie P. (NY)]

US - Lousiana 156th Infantry (and back to National Guard in peacetime). Activated in 1940. I'm guessing wuth the screw back that is WWII era.

 

[Catahoula]

Wow, Charlie, you're fast! Thank you very much... I've Googled until my fingers are cramping with no luck. Thanks again for the help.

 

[nhbenz]

Good info., here's more about the 156th: http://en.m.wikipedia.org/wiki/156th_Infantry_Regiment_(United_States)
The background on the collar disc would seem to indicate that it dates 1926-37: Dating Metallic Insignia: Collar Disks -type II, right?