Undergarments or outer garments? Dress or work shirts? Metal four-hole buttons with paperboard backing were common for both. Undergarment buttons could be bone, wood, glass, tin, celluloid, nacre, or hard rubber. Outer garment buttons were typically the same materials as well. The ones supposed to be visible would be larger and more decorative, while the ones not supposed to be visible would be simple and utilitarian. Buttons for dresses and formal coats would usually be colorful and decorative. A cowboy's shirt button would usually be something cheap like small tin or bone, and would be bare metal or unpainted bone. A cowboy's jacket would have large bone, metal, wood, or hard rubber, and if not specially decorative would be brown or black, or bare metal.