'Stone'-Looking things coming up in mouth?

I don't think that this is so life threatening that I have to go see a doctor, but over the past few years I've had these small white pebble-looking things coming up into my throat and getting stuck there for a few hours, then coming into my mouth.. They don't have a particular taste, but smell very very foul and are usually soft, except recently they have been coming up more often.. every week or two, and they are a bit harder. Any help on what this might be? There shape and color are consistent.