These are simple 15mm circles used to lift your workpiece. This is useful when laser cutting so that smoke and heat can pass under the object. I currently use these instead of a honeycomb bed. This was one of the early things I cut. You can use simple scissors to cut cardboard pieces for this as well, which is what I suggest you place under the board for cutting these, but it's nice to have nice clean circles to lift your workpiece.
You could also use coins for this purpose. A penny or nickle would probably work fine.