Turn it over. If there is a bead that goes around the bottom of the pan and a number.....don't cook it in. SELL it! Because it is very very old and cast iron pans/pot collectors go ga ga over them AND you even have the lid! :C
I scored 4 old rusted Griswold skillets and one pot at a farm sale and sold them for over 100 each! There's one on ebay right now for $250.00.
http://www.ebay.com/itm/GRISWOLD-Cast-Iron-SKILLET-Frying-Pan-11-BLOCK-LOGO-Heat-Ring-RESTORED-/301981754809?hash=item464f83e5b9:g:6fAAAOSwOVpXW2DpLodge is one of the very desirable ones too. They can be a hundred years old. If a pan has one or more notches in the heat ring, it is likely a vintage Lodge.
Do you have picture of the bottom of pan and lid to post?