I have had a few questions;
Trench are can be any era, any war, any country. I will make some determinations, but essentially it can be made of brass (WW1 comes to mind), designs on the brass (shell casings), large shells and small shells.
Wood markings, sometimes initials, but unit marked, names, etc, I have 4 or 5 Japanese examples in Veteran Bring Backs Vol II.
So, if you have something that is unique and is likely from a GI or possibly GI market, send it to me in hi-rez, I will look it over, but this book is intended as a interesting reference and I will divide the book into sections and if enough evidence, into separate countries.
email to:
ed_tinker@hotmail.com
Ed