These are often seen on the browbands of bonnets in the place of beadwork, as well as decoration on wool bags, dresses and other articles where a large brass disc provided beautiful contrast and shine.  We had these made exactly to our specifications, they are flat with a ring on the back for securing.  The metal is solid brass and heavy enough to be substantial but not excessive.  

Brass Flat Buttons 3/4" (10 pack)

SKU: BFB-19mm