Scio Ransom Platter

I've been collecting these dishes marked USA for years and never been able to definitively identify the maker, but believe they are Scio and the shape is ransom. I started collecting them because my mother and grandmother had sets of these when I was a child. They are rather hard to find without chips or cracks because they are quite brittle. This platter is 12 x 9 inches and is without chips, cracks or breaks. There were 2 sizes of the platter manufactured and this is the largest. There are some light utensil marks, manufacturing fired in spot and one tiny faint discolored spot. The color setting was wrong for this photo and it does not show that it is white - not ivory. Please email questions or additional photos. I also have vegetables bowls, dinner and salad plates in this pattern are available. I need your zip code to calculate the postage.