Last week when my 4 year old granddaughter was visiting for Chistmas, we unpacked a box from our attic containing my old little girl dish sets. There are only a few pieces of the oldest set left, a blue on white design of 2 Dutch children by the sea with a sailboat in the background.
I have only 1 small teacup and 3 saucers left, but remember them fondly from playing with them in Baltimore. My daughter played with them in the 1970s and now her daughter (and son, too) enjoyed a little tea party last week.
They are labeled "Edwin M. Knowles china Company / Made in the U.S.A./ 42-10.
They are also labeled semi-vitrous. I recall having tea parties with my new friends in a Baltimore suburb, Parkville, after we moved out of the city when I was 3 years old. I was delighted to find the company when I "Googled" the name.