old glass refrigerator dish lid

This old glass lid was found upside down stuck into the bottom of a wire-basket planter to keep excess water from leaking out. Glad I happened to notice it there, its far too interesting (and likely far too old?!) to have to live the rest of its life like that.

I'm thinking this certainly would have been the lid for one of a glass 'refrigerator dish' set. It measures about 4" x 8-1/2" with a rectangular ridge around its inside and (after I scrubbed years worth of lime deposits and grunge out of it) a 'vegetables pattern' decoration including corn, tomato, carrots, and asparagus. Its outside is smooth and slightly 'dished' (so's you could stack a 2nd one on top safely) with little 'handles' in the middle of its sides and accents at the corners.

There's one small chip at one corner -- otherwise its perfectly intact. There are no maker's marks evident, and I don't really know how old it is, but would guess 1940's-50's. Does anybody else recognize anything about it??