Lost On The River: The New Basement Tapes is a music event 47 years in the making. It’s an historic album project from five of music’s finest artists — Elvis Costello, Rhiannon Giddens (Carolina Chocolate Drops), Taylor Goldsmith (Dawes), Jim James (My Morning Jacket) and Marcus Mumford (Mumford & Sons) — in unique collaboration with a 26-year-old Bob …