The 72-year-old West Bromwich-born singer-songwriter revealed the existence of the large collection during the first episode of the fourth season of his Digging Deep with Robert Plant podcast.
He told co-host, Matt Everitt, the recent lockdown had allowed him to put his house in order.
“All the adventures that I’ve ever had with music and tours, album releases, projects that didn’t actually get finished or whatever it is, I just put them, itemised them all, and put everything into some semblance of order,” he explained. “I’ve told the kids when I kick the bucket, open it to the public free of charge. Just to see how many silly things there were down the line from 1966 to now.”
The archive also includes personal items including a letter from his mother saying: “Look, you’ve been a very naughty boy, why don’t you come back, because Sue wants to know where you’ve gone. And also, the accountancy job is still open in Stourport-on-Severn. Why don’t you just come back home and we’ll just pretend all this stuff didn’t happen?” “I hadn’t opened the letter until about three months ago,” he said.
He will be performing at Dudley Town Hall as part of his tour with current band Saving Grace on July 26.
The tour also includes concerts at Tenbury Wells on June 22 and Severn Theatre, Shrewsbury, on June 29.
The singer, who now lives near Kidderminster, was with with Led Zeppelin from the late 1960s to the end of the 1970s.
In 2008, Rolling Stone editors ranked him number 15 on their list of the 100 best singers of all time.
He released Digging Deep: Subterranea, a compilation album featuring solo performances in October last year.
The songs were assembled as a companion to his podcast series Digging Deep, exploring his post-Led Zeppelin career.