They include a previously unheard recording called La La, as well as early versions of more familiar songs by the music giants, who reunited for a celebrated one-off performance in 2007.
The archive material is to be included on remastered versions of the band's first three albums which are to come out in June, the first batch of revamped versions of their nine studio albums.
Deluxe editions of each of the first three albums - to be released on June 2 - will come with a separate disc of extra songs recorded by the band, made up of Robert Plant, Jimmy Page, John Paul Jones and the late John Bonham.
Announcing the remasters, which will come in a range of formats, guitarist Page said: "The material on the companion discs presents a portal to the time of the recording of Led Zeppelin.
"It is a selection of work in progress with rough mixes, backing tracks, alternate versions, and new material recorded at the time."
The group's self-titled debut will feature a previously unreleased live album from the Olympia venue in Paris, recorded on October 10 1969, which includes a 15-minute performance of Dazed And Confused.
The extra disc to accompany Led Zeppelin II features different mixes of songs from the album as well as the unreleased La La, and backing tracks for Thank You and Living Loving Maid (She's Just A Woman).
The extras for Led Zeppelin III will include outtake versions of album tracks as well as an embryonic insrtumental version of Bron-Yr-Aur Stomp called Jennings Farm Blues, a vocal-free early version of Out On The Tiles called Bathroom Sound and a recording of Keys To the Highway/Trouble In Mind.