The CD also earned the pair the prize for best contemporary folk/Americana album, while their song "Please Read the Letter" won the record of the year honor, their track "Rich Woman" won them the Grammy for pop collaboration with vocals and their single "Killing the Blues" earned them the award for country collaboration with vocals.
"When we started this project together, the whole game was a mystery," rocker Plant said of his foray into bluegrass and country music, as he accepted the award for "Letter."
"We brought this song out. It's an old song that Jimmy Page and I wrote post-Led Zeppelin and it's been given that Nashville touch and it feels pretty good. Thank you."
Swim Week Miami Beach 2014 [PHOTOS]