ADF stoneware mead beer stamped "ADF"

[Pawnster]

This stoneware beer is part of a lot of assorted bottles advertised on Craigslist last year. The bottle is stamped on the shoulder "ADF". It's in nice condition with no cracks or chips and is marked with some heavy rust stains. Also in the box was a San Francisco Belfast hutch, an antique stoneware soy sauce bottle, an old stoneware ink, numerous California apothecary bottles, and many nondescript bottles. The whole box was $30, and was acquired from a seller in Salinas, California. I have been unsuccessful at finding any reference to this ADF stoneware beer. The "F" is partial but there is enough there to convince me it an "F". Can anyone lend any tips on identifying this example?