This is a Jackson China USA restaurant ware red floral and seagull pattern single bouillon or custard cup. I have also seen it called a sake or tea cup. It is 3" wide and 2 1/4" tall, in excellent condition with no chips or cracks. The backstamp is green and reads "Jackson Vitrified China Made in USA Falls Creek, PA."
Jackson China Seagull Red Restaurant Ware Cup Custard Bouillon