Marshall had the ordnance laboratory (powder works), a branch of the Treasury Agency, and the Trans-Mississippi headquarters of the postal service, as well as the headquarters for the Confederate Missouri government for a while. Gen. Elkanah Greer ran the conscript service out of Marshall, his home town. I'm sure it must have had an official post, like Tyler and Crockett (among others), but I didn't pick it up in my abstracting work out of the Marshall Texas Republican ( http://www.uttyler.edu/vbetts/marshall_texas_republican,%201863-5.htm ). It might be worth your looking through that microfilm again (note that there is a gap when they ran out of paper), or checking the card file index to early Texas newspapers at the Center for American History at the University of Texas at Austin for the name Squire Boone or S. Boone. Receipts from the agencies and posts mentioned appear in Footnote.com's Confederate Citizens and Business file. I haven't found a Boone signing any general receipts (for whatever that is worth) but most of those that have survived are pre-Vicksburg. I may come across some yet in my annotating project. There are receipts from Marshall for 1861 and 1862 as troops were organizing and moving east. Most are signed by assistant quartermasters, particularly A. M. Truit. Others are signed by the colonels of the regiments moving through.
I checked the archeological report on the Marshall powder mill site, just to see if the author had found any correspondence between the powder mill and the post in town, but there was none. The author does cite the scarcity of written sources for Marshall, often relying on Col. Hill's correspondence from the ordnance works in Tyler that refers to Marshall.
In short, the answer may be that there just isn't much paperwork that survived out of Marshall from the second half of the war. If anyone knows of additional sources, please respond!!
Vicki Betts
Tyler, TX