The 2 songbooks we generally use are:

 
Bluegrass Songbook
by Pete Wernick
Over 130 songs, also includes excellent preface and appendix information on bluegrass playing.
 
Parking Lot Picker's Songbook
Mel Bay Publishing
Over 225 songs, comes in instrument-specific editions, comes with audio CDs

Both of these books are available from local music stores, Amazon, and online music retailers.

Dr. Banjo has a list of popular bluegrass jam favorites.

Songs that frequently show up at our Jam:

New Favorites:
Long Journey Home (Two Dollar Bill)
Sitting on Top of the World
Roving Gambler
Wagon Wheel*

Old Favorites:
Roll in My Sweet Baby’s Arms
I’ll Fly Away
Amazing Grace
Will the Circle Be Unbroken
Mountain Dew
Dooley*
Old Home Place
Banks of the Ohio
In the Pines
Rocky Top
Nine Pound Hammer
Salty Dog Blues*

Songs marked with an asterisk (*) are not found in the songbooks above; email us at info@camelcitybluegrass.com for a song/chord sheet (pdf format).