Loretta Lynn has rightly become associated with her feisty, no-nonsense solo country hits, but her successful run as a collaborator deserves its own recognition. She was perfectly matched to fellow country singers like Conway Twitty (her longtime duet partner) and Willie Nelson, scoring hits with both, but expanded out of her comfort zone in unlikely-but-great meetings with Jack White, Elvis Costello, and even Frank Sinatra. Here are Lynn’s finest collaborations and duets, from “Portland, Oregon” to “Louisiana Woman, Mississippi Man.”