yes that would be a saucer for a cup set, hence the ring in the center, ones without the ring in the center is called a Bread Plate. And you are correct about needing to know the pattern name. I have tried to sell saucers without cup to no avail, and if you have the name maybe someone can find it for a missing or broken piece. However the most common part that is broken is the cup. I'm sure you have looked at replacement, which sometimes can be daunting to look through.