Columbia/Legacy put out more unreleased Johnny Cash
yesterday with the third volume of its "Bootleg"
series. This one collects material from the Big "D" Jamboree in Dallas (1956), New River Ranch in Rising Sun, Md., (1962), the Newport Folk Festival (1964), USO tour in Vietnam (1969), the White House (1970), Osteraker Prison in Sweden (1972), CBS Records Convention in Nashville (1973), Carter Family Fold in Virginia (1976), the Wheeling Jamboree in Wheeling, W.Va. (1976) and the Exit/In in Nashville (1979), according to CMT
I haven't gotten to listen yet (stupid Spotify!), but volume one's filled with some gems.