If I may, Butternut is what you get when you dye wool in walnut oil. I don't know the precise recipie but yes they had whole regiments of butternut, particuarly in the Trans-Mississippi and Army of the Tennessee, where Gray dyes were not so readily available. Some Unit uniforms were dirty white and some greyish white.

My Butternut Vest, grey/green/tan pants and white shirt were common in the Trans-Mississippi and many variations to boot. I also were civilian brogans as I try to portray a civilian/militia style soldier.

I apologize for butting in,,,