The Mystery Dish is a Domino Tray. It was used to hold sugar cubes around the side and a creamer in the center. This domino tray was made by Hocking Glass Company between 1930 and 1934 and is the Cameo or Ballerina or Dancing Girl pattern. The Economy Glass Company is the only other glass company known to have made the domino tray and it was made in their Round Robin pattern. Hope you enjoyed the mystery.
The first person with the correct answer was Annie Lema, visit her FB Business page sometime. http://facebook.com/fabquirksbyannie