A Bromfield Street Fixture For Over Thirty Years Originally the John Dean Coin Co., Bay State Coin Co. has been located at 31 Bromfield St., the heart of the Bromfield Street “coin district,” for over thirty years, since 1981. Bay State Coin Co. buys and sells coins, stamps, gold, silver, diamonds, watches, jewelery, antiques, and a vast variety of memorabilia–political buttons, toy trains, baseball cards–and much more. Bay State Coin Co. will match any competitors’ price, provided it is reasonable. They are “here to help people,” and honest and fair, as their volume of repeat customers attests.