Hi Mary: Buttons like this are not common but they are also not very valuable. Not many collectors for jumbo buttons like this unless they are very ornate. Abalone can be a very large shell, or they used to be before that sea creature became overharvested and endangered. Buttons like these were often put on "duster" coats. A cloth coat kept in the trunk of a "roundabout" open top auto. The long cloth duster coat would keep the riders clean and they often had really huge buttons on them. Or a button like that could have been embellishment on a garment rather than one which would actually go thru a button hole.
