Everybody's right. You're embarking on a major journey. Do you sing, play an instrument or listen to the old songs? That means you'll appreciate more what's in allthose books and links. On the other hand, your job is easy compared to the scholars and musicians who have traveled all over collecting from the singers and transcribing songs remembered from family and friends' singing.

For me, American folksong falls generally into two categories: Native and Naturalized. Naturalized songs and ballads were brought here by people who came from other places; native songs have to do with events that were documented in music in the US. Those songs all document history so much more vividly than any third-person history book account of what "they" did. They're primary sources of information about what was: wars, crimes, politics, family life, work--you name it!

Good luck in your searching, and above all have fun. Joan