I have seen several cast iron griddle pans at flea markets....round, flat, shallow, like many I have seen photos if here, but they have the raised grids. Every one that I saw had no markings on the back. I have done many internet searches looking for pans such as this but have only come up with photos of the flat smooth griddles. Are these ones with the raised grids newer? Any help appreciated as I am going to a large flea market this weekend and would like to know if these are older and worth buying/collecting.