To make these stoppers, I pair a base wood with a disk of contrasting endgrain or exotic wood. The top is then turned to a gracefully curved cabochon shape shown below. I use "Flor" cork which is the finest grade of cord available. Flor corks have few "pits" and are more dense. Wood species are listed at the bottom of the photo.
I harvest my own end grain stock from small fallen limbs and shrub prunings. My exotic wood is gleaned from the "scrap" cut offs of other wood working shops.
All of these stoppers are slightly less than 2" in diameter, the cork diameters are such that they seat deeply in most bottles.