In both "A Name for the City" and Requiem for a Nun, this unprepossessing "small leanto room like a wood- or a tool-shed" is the original "Yoknapatawpha County courthouse" (201, 4). It was constructed against the side of the (partially dismantled) jail on the day the settlement got its name, and had its "consecration or ordination or whatever you call it" as a courthouse two days later, when the residents moved an iron box full of records into it (201, 4).
The "blacksmith back in Cal'lina" who made the lock for Holston comes into the story when Ratcliffe proposes that the settlement pay him to make another lock to replace the one that is lost; he goes out of the story when Ratcliffe's idea is exploded by Pettigrew's intervention (212).