I collect old books, I am often in charity shops thumbing through them looking for titbits.
I go for a, books that interest me, b, books in good condition (all pages etc), c, with topical titles/authors reletive to parts of the house and d, books with handwriting in front cover, presented to, given too, these will have a date etc. The oldest one I have to date is 1896 given to a pupil by his sunday school.
I have an Insurance Association book from 1953 listing all cars and light trucks at the time and includes standard quotes,times for accident repairs. my gem is a county engineers typed diary from 1920's detailing his daily tasks over 10 years, very interesting as I live in said county and can see some of the thing he saw and wrote down including some of the works he got done.
I also have a large collection of Womens Studies books used for a degree.
Oooops gotta go to work, can go on for hours....may be later folks