I've known about G. Gedney Godwin for about as long as I've been in the hobby. Although he's also known as The Sutler of Mount Misery, I better know the business by the name. GGG serves mostly F&I and Rev War reenactors, and has a large selection of goods from these periods. A Civil War reenactor could probably find some decent knick-knacks like the period pocket knife, but it takes some careful looking and research to see what fits.
The G. Gedney Godwin site has plenty to see, it's easy to surf, and a nice bookmark if you're into the 18th century scene.