Hameln's old town has a concentration of cafes and restaurants aimed at day visitors. The Rattenfängerhaus restaurant in the historic building of the same name (Osterstrasse 28) is the most atmospheric option — the prices reflect its location, but the setting, inside one of Germany's finest Weser Renaissance buildings, is hard to beat.
For something less expensive, the market square and surrounding streets have bakeries, cafes, and the usual range of German casual dining — currywurst, schnitzel, and the like. On weekends the farmers' market on Market Square has fresh produce, cheese, and local foods worth trying.
Regional specialties from the Weserbergland include trout from the local rivers, asparagus in season (May-June), and the usual north German pork and potato dishes.