One may find a lot of the old time songs by going through the comprehensive lists of songs and performing artists in Michael Kilgarriff, 1998, "Sing Us One of the Old Songs," A Guide to Popular Song 1860-1920, Oxford University Press.
Check the song titles against the several sites which have song sheets and/or sheet music, such as the Levy Collection, American Memory, The Bodleian Library, National Library of Scotland, and the Murray Collection, as well as google, and a number of them will be found.

There also is a volume covering older material, but can't remember it offhand.