We have had at least a couple of threads on songbooks - Click here and here and here.
You're right, Dr John - while there are lots of songbooks, the books don't tell much about the people who sang the "real" folk music. There are plenty of biographies about the collectors and the people who recorded professionally, but they are not the source of true folk music. Maybe that's the key - folk music comes from ordinary people, not from celebrities.
Maybe I shouldn't dismiss the songbooks and collectors quite so quickly. Some of the collectors told wonderful (but brief) stories about the people who sang the songs. You have to read songbook introductions and footnotes - and it can make fascinating reading, if you take the time to do it.
-Joe Offer-