The plate which the pastries are on is a Johnson Bros. Friendly Village - The School House dinner plate which was first produced in 1953.
Elizabeth implies that the reason the one egg keeps spinning is because it's liquid inside and "the liquid keeps moving because of the law of inertia." This is wrong and as a teacher she should know it. The egg that keeps spinning is the HARD BOILED egg, not the raw egg. Raw eggs are the ones that resist spinning in the first place because they are liquid inside.