Have found a few reference on the net to this pattern. Replacements has it listed but none are available. Ruby Lane has a 12" Platter going for $24.00. So we have a pattern that has little availability, Nice Pattern almost call it semi-fancy. This in it self will limit the collector base on these items. Meakin has good name this will help. With the hallmark we know it is post 1890, doesn't help too much. I would say you are looking at a Post 20's, Pre 40's pattern, again this is a guess. Platter at $24.00, Platters being usually mid collectible level, (dinner plate low, Tea cup High). Dinner plate $5 to Teacup $30.00. Would gamble it to be a slow market mover, but would move. Keep in mind this would be items in excellent condition, damage, chips and etc. about 25% of value. the only other comment I would add is the guy who sold them to you said 1890, that is when this stamp was beginning to be used and could and most likely much later.