Sugar Bowl - MADE IN USA under F - Help ID

by Mary Ware
(Lexington, Kentucky)

I have a light solid bluish-green sugar bowl with lid and creamer in a very soft top to bottom swirl pattern. On the bottom of the sugar bowl is a stamped mark of a capital F in a square box with "MADE IN U.S.A" under the boxed F. Can you tell me anything about this mark? Can you tell me if this is of an antique quality or value?

Thx,
Mary