Maxwell and Williams white basics ramkins. They come in a range of sizes and are surprisingly cheap. They start at $1 for he smallest size (haven't measured it but it's tiny), you can get them from homewares stores such as House, Robin's Kitchen and the like. There are other stores which sell "cheaper" versions....though they're really not cheaper by much if anything, but I've found you can get a better range of sizes with the M&W ones.