Set of 3 footed mugs made by Federal Glass in the Old Town Blue or Blue Onion dinnerware pattern by Pyrex Corning Corelle from the 1970s. The handles are in the shape of a heart. The Old Town Blue design consists of a navy blue design decal on white glass. This glass is heavier than Corelle Vitrelle. The Pyrex Corelle Old Town Blue was made from 1972 to 1978. I am not sure when the Federal footed mug was produced, but assume around the same time era.
Each mug stands about 4 3/4 inches high with about a 2 3/4 inch diameter opening. There are 3 embossed markings on the bottom and are very hard to see. There is U.S.A. - see picture. There is the F inside a shield - see pictures. There are also 2 numbers that I could not get a picture to take - 2 mugs looks like a 4 and a backwards 3. The 3rd mug looks like 20.
The markings are very hard to see at first glance and you have to play with the lighting to see them.