Going through a warehouse crammed with 50 years of archival material yielded things Steve Miller had forgotten about, as well as things he didn’t even know existed, as he prepared for his new catalog deal with Capitol/UMe and the upcoming Ultimate Hits set.

Among those was the previously unheard, lush but also austere version of “Seasons,” from sessions for 1969’s Brave New World album. “I had stopped looking around for ‘Seasons,'” Miller tells Billboard, “and we were going through mixes and cassettes and looking for thins and we found this version of it — and I thought it was better than the original one. I didn’t even know it existed. I don’t even remember doing it. I have a really good memory; I usually remember almost everything I’ve done but I was just really surprised by that version of it. I think it’s the best version, so I was happy to find it.”

Ultimate Hits, due out Sept. 15 in single- and double-disc deluxe versions, feature three and eight unreleased tracks, respectively. The compilation, personally curated by Miller, is the Rock and Roll Hall of Famer’s first gambit under his new deal, which puts his entire nearly 50-year output under the same roof.

“I had controlled different parts of (the catalog),and I had different companies around the world releasing it here and there,” Miller says. “The 50th anniversary is coming up next year, so we decided it was time to just start looking at everything and put it all together, and create a situation where we can have one company represent it worldwide and coordinate all the reissues and everything. It’s turned out to be a really good idea.”

A vinyl box set, also with bonus tracks, is being prepared for 2018, along with more touring to commemorate the 50th anniversary of his first two Steve Miller Band albums, Children Of The Future and Sailor. And Miller confirms that his vaults — which he considered simply throwing out until his wife and some archivists intervened — are brimming with treasures. “There’s a lot of things that Paul (McCartney) and I did, probably eight or nine things that we recorded that I never released,” Miller says. “There’s some really interesting pieces with Brian Wilson, and there’s some great blues stuff that I did with Cannonball Adderly that’s more of a blues-jazz project.

“There’s a lot of live performances with lots of great artists that I toured with over the years,” he continues. “There’s some really good stuff with Paul Rodgers and Neal Schon…Oh gosh, there’s just so much of it. There’s lots and lots of live shows with different artists.”

Miller — who also serves on the Board of Jazz at Lincoln Center and on the board of the Metropolitan Museum of Art’s Musical Instrument Department — won’t only be putting out archival music, either. “I’m writing new material now,” he says. “I’m still interested in making records and recording music. I think just taking all this time took at this huge archive and study it and pull things together, it makes you want to write some more things. The best part of it is I haven’t lost my appetite for the work. And now we’re planning next year’s tour and I’m really excited about all that stuff.”