One thing I cannot call is the the worth of glass. I watch Antiques Roadshow in awe when a vase or small paperweight racks up at a few hundred or even thousands of dollars. Seems like this would be a good entry level though... post-Depression era Fire King. Fire King was a branch of Anchor Hocking, a US based glass manufacturer since 1905, best recognized for measuring cups and ovenwear. Not surprising, Anchor Hocking has a great anchor logo, for that nautical kitchen look.
These milky white coffee mugs used to be a thrift store staple but to find sets is tough. Inevitably they are hugely collectable items in Japan. The greeny, Jade-Ite stuff was blownup by Martha Stewart on her show about 10 years ago. So if you already own some at home, thank Martha.
You can really delve into the markings etc at FireKingMugs but ebay (natch') has a million auctions for the