If you want to stack your buttons, you can sew them together before attaching them to the finding. Sew through them once or twice and tie a firm knot on the underside. I used a mixture of vintage and new buttons.
Sew right up through all the button layers if possible, lining up the holes as you go. If you can’t sew through the buttons, just sew the disc to the buttons by passing the needle through the knot on the underside. Sew them on firmly, and tie off your threads at the back or weave them back in under the disc to hide the ends.
Show off your bling! When you get bored with the buttons, you can just snip them off the disc, return them to your stash, and make some new rings.