"I'm gonna talk to 'em, say, 'You teeny-boppers, I wouldn't expect you all to be here at church,'" she said, then burst into a low, throaty chuckle. "That might get a rise out of 'em."
The annual festival, which takes place in Indio, Calif., is known for its audience of pleasure-seeking 20-somethings, not exactly a natural fit for Staples' rough-hewn songs of resilience and faith.
So the 76-year-old soul and gospel veteran was pondering how best to connect with people before they skipped off to be happily pulverized by Jack U's hammering electronic beats. Turns out she needn't have worried: An hour or so later, Staples was standing in front of a good-size crowd, drawing big cheers with a lively set as funky as it was devout.
Part of what the audience was responding to was Staples' energy, which is running nearly as high these days as it did in the 1960s, when she was helping to soundtrack the civil rights movement with her groundbreaking family band, the Staple Singers.
In February, she released a strong new album, "Livin' on a High Note," her seventh record since 2004. That same month, HBO premiered a documentary about her titled "Mavis!"
And the Coachella dates come shortly before Staples, who lives in Chicago, will hit the road as the opening act for her old friend Bob Dylan. She will perform Wednesday, May 4, at the Broward Center in Fort Lauderdale and Friday, May 6, at the Kravis Center in West Palm Beach.
"I never thought I would be singing this long," she said. "And to be heard at this point in my life? All our shows are sold out. I just thank the Lord because he's not through with me yet. He's telling me, 'Mavis, I got much more for you to do.'"
The Lord isn't the only one not finished with Staples.
To produce "Livin' on a High Note," she recruited indie-rock singer and guitarist M. Ward, who commissioned new songs by some of his peers: Justin Vernon of Bon Iver, Merrill Garbus of Tune-Yards, Neko Case and Ben Harper.
In their tunes, you can sense their respect for Staples and what she symbolizes, but also their expectations of her as a working musician. "Jesus Lay Down Beside Me," written by Nick Cave, has tricky intervals and a lyric that requires real gravitas to put across.
"Livin' on a High Note" follows collaborations with Wilco frontman Jeff Tweedy, with whom she won a Grammy for 2010's "You Are Not Alone," and Ry Cooder, who produced 2007's "We'll Never Turn Back."
Staples called her creative partners "the geniuses." (Cooder, at 69, is "the senior genius.")
Another person she learned to trust was Jessica Edwards, the filmmaker who directed "Mavis!" The movie notes that Dylan proposed to Staples in the '60s. "I don't know how that little girl got me to tell as much as I did," Staples said with a laugh. "But Bobby and I, we were in love. We smooched."
The story has become something of an object of fascination among music fans, in part because it humanizes a woman thought of as a moral icon.
"With me being a gospel singer and a Freedom Rider, people just think …" Staples said, trailing off. "I don't think they think I'm holier than thou, but they don't look at me as even having a boyfriend. It's like I belong to them.
"But it was real," she said of her romance with Dylan. "And I often think about it. Had I married Bobby, we would've had some little crumb crushers, and they'd be singing now. We would've had us a family group: the Stap-Dylans, or the Dylan-Staps." She laughed.
"Now, I know where we're gonna be in June: We're gonna be pushing each other around in a wheelchair," she said. "I'm gonna have to tell him just like I told him back then, 'Cool it, Bobby.' He'll say, 'Mavis, let's go out tonight. Let's go dancing.' And I'm gonna try him. I'll say, 'OK, let's go.'"
Mavis Staples and the Blind Boys of Alabama will perform 7:30 p.m. May 4 at the Broward Center for the Performing Arts, 201 SW Fifth Ave., in Fort Lauderdale. Tickets cost $50-$125. Go to BrowardCenter.org. The concert will also take place 8 p.m. May 6 at the Kravis Center for the Performing Arts, 701 Okeechobee Blvd., in West Palm Beach. Tickets start at $20. Go to Kravis.org.