I am in NE Texas,, born in Dallas and lived in Mesquite !!
Is there some reason your Grandmother could not have either purchased it or possibly it was given as a gift to her at that time?? When you stop and think about it mid century would be 66 years ago ( I was born in 49 ) !! Or slightly earlier !! So 1940 to 1960 !! Why do you think its older than that ??
There is no makers mark or stamp and no artist/designers signature !!