WM Rogers Silver Plated Tea Set

I have this set from my grandmother. The marks on the bottom are wm rogers - the eagle/star combo - and there is a sticker over this mark that says International Silver Company. Very heavy set. The spoon says "Italy silver plate" - the other tray does not appear to be part of the set - it is stamped WM. A Rogers with no pictoral marks. Likely that the additional tray and spoon are not part of the original set. Any idea of value?