Thanks for the reply
From the backstamp, the set ins from 1915-1920.
Regarding the value of your item, I have just perform a market research of similar sold items as yours. I performed the research based upon the most recent finished auctions and private sells, so the value given is the real market value of your item. This is the only way to know the exact value of your unit.
The value will be in the range of
Dinner plate - 20$ for each unit
Cereal bowl - 12$ for each unit
Small bowl - 11$ for each unit
Large platter - 100$ for each unit
Small platter - 50$ for each unit
Soup tureen - 90$ for each unit
Sugar bowl - 30$ for each unit
Gravy boat - 40$ for each unit
If you want to sell the unit I would recommend to sell them on the internet so you can reach more potential buyers. You can also sell the lot locally, Craigslist is free, and a lot of collectors look at the ads on Craiglist.
Keep in mind if you sell the unit to a resell shop, the price will decrease 20-30% from market value.
You can sell the item on Etsy, it's like you put the item in a online shop. You may also check Amazon Market Place. Both places have good reputation, and you can easily sell the items for a good price.
Let me know if I can help you any further, otherwise, please, remember to rate my answer!