"This collection contains letters to and from Martha Washington that have been acquired by the MVLA since 1858. For more information, see content note for individual items. The collection grows organically as new items are acquired."
Suggested terms to look for include - diary, diaries, letters, papers, documents, documentary or correspondence.
Combine these these terms with the event or person you are researching. (example: civil war diary)
Also search by subject for specific people and events, then scan the titles for those keywords or others such as memoirs, autobiography, report, or personal narratives.
Off campus access instructions (for e-books)
Memoirs of the Mother and Wife of Washington by 
Worthy Partner : the Papers of Martha Washington by 
The Papers of Martha Washington by 