The Special Collections Research Center (SCRC) has extensive holdings of manuscripts, university archives, and rare books. There are a variety of tools available to guide you in finding materials in the SCRC, including the SCRC Collections Database. You might find it helpful to begin your search at the SCRC's Search Tools page.
Don't forget that you also may contact the SCRC staff (spcoll@wm.edu or 757-221-3090) or come into the Special Collections Research Center in person and consult with the staff member on duty for guidance.