Collections of letters, diaries, and other documents or resources produced in the home contain information about the daily lives of their creators. Through these records can be found mention of enslaved persons, free people of color, and the context of the community they lived in. These can be the most rewarding sources to read, but they are also the most scattershot, as there is no way to predict when an author will make comments that relate to the study of BIPOC Valley residents.
Historic Deerfield has compiled a useful "Guide to Resources in the Collections of Historic Deerfield Library and Pocumtuck Valley Memorial Association Library (PVMA) related to Slavery" that describes materials present in diaries and family papers in those collections; it can be consulted here.
The Sylvester Judd Manuscript at Northampton's Forbes Library is also an important example of a valuable collection of personal papers. A Northampton newspaperman and local historian, Judd filled some sixty notebooks with information about the social history of the Valley. Many of these are arranged by town, though there are some 15 volumes in a series titled "Miscellaneous." They are housed in the Hampshire Room for Local History at the Forbes Library in Northampton.
University of Massachusetts Amherst Special Collections and College Archives.