I found this place that makes underwear for the US military. They're 100% cotton and the prices are good. $6 for a 3 pack. I ordered 4 packs and shipping was $12, so my total was about $36. So that's $3 a pair. They only come in brown and sand. They also have tee shirts. They are located in Kentucky, my ancestral home.
http://www.camapp.com/
If Colin and Dennis approve this thread topic, please add any products you may have found that are USA made. What the heck, I'll even buy from Canada.