According to USGS: Geographic Names Information System (containing "entries for almost 2,000,000 geographic features in the United States"), there're two Sourwood Mountains on the record.
(1) Sourwood Mountain -- St: TN -- County: Jefferson -- Type: summit -- Latitude: 360428N -- Longitude: 0833456W
(2) Sourwood Mountain -- St: VA -- County: Russell -- Type: ridge -- Latitude: 370111N --Longitude: 0820820W
Other Sourwood names include Sourwood Spring (AL), Sourwood (KY), Sourwood Branch (KY, SC), Sourwood Creek (MS, TN), Sourwood Gap (NC), Sourwood Mountain School (school; VA), and Sourwood Ridge (WV). No Massachusetts place name is among them.