From PEOPLE Magazine Click to enlarge
What kind of a suitor is John Mayer? The kind who sends cards and flowers. The kind who makes the new object of his affection, Jessica Simpson, "giggle," according to a source close to her. And the kind who passed the 'Daisy' test with flying colors. In the few months Mayer and Simpson have been an item, says the source, "he has even babysat for Daisy"—Simpson's beloved maltipoo mix. "If you're in with Daisy, you're in with her!"

Take it from Daisy: Mayer, 28, is officially in with Simpson, 26. And the bubbly pop star—whose promotional tour for her new album, A Public Affair, has been slowed by a bruised vocal cord—can hardly contain her delight at falling for the scruffy-haired singer-songwriter with a sensitive streak. "She's head over heels," says the source close to her. "She's telling friends, 'I'm in love.'"

So how did the opposites-attract pairing—the music-industry equivalent of the head cheerleader hooking up with the sweetly geeky drum major—happen in the first place? After meeting at Clive Davis's pre-Grammy party in 2005—when Simpson was still married to Nick Lachey, 32—the couple "bumped into each other" in June at New York City nightclub the Double Seven, where a source says Simpson was "flirting up a storm" with both Mayer and actor Jared Leto. The singer was especially smitten when Mayer praised her new single, "A Public Affair." "He flattered her," says another source.

Nearly 10 months after her high-profile breakup with Lachey, the low-key Mayer appears to be the right guy at the right time. The Fairfield, Conn.-bred musician—who won three Grammys by age 27—"is a smart East Coast boy," says the source. "John's got depth and humor and talent. He doesn't hang out at Privilege [a night club] until 3 in the morning. As cute boys have hurt her, she's realizing she doesn't have to be with the cutest frat boy in the room."

To hear him tell it, Mayer—who is currently touring with Sheryl Crow and who has a new album, Continuum, due Sept. 12—wasn't exactly looking to date the popular girl. "I just don't go for celebrities," he told PEOPLE in July. "I've met people that are, like, supposed to be the sexiest woman on Earth and they actually suck the chemistry out of the room. The celebrity mentality is a whole different fate than my fate." Still, he openly expressed his desire to be in a relationship. "Nobody really wants to be single," he said. "They always say if you don't look, you'll find it. Well, I have not been looking for a while and I haven't found it. I'll be willing to give up anything at any time in my life for the right thing."

So is Mayer Simpson's Mr. Right? Although the singer told Glamour magazine in its new issue, "I feel good being married to myself right now," sources close to her say she is savoring the new romance. "They've barbecued at her house," says a Simpson insider. "She's just started gardening, and he impressed her by knowing all the flowers she planted." Mayer is also "the antithesis of Nick," says the source. "He makes her feel special and beautiful and smart. Nick used to laugh when she said something that didn't sound smart."

Although Lachey has been romancing MTV and Entertainment Tonight personality Vanessa Minnillo, 25, since March, Simpson has been "tiptoeing back into the dating world," says the source close to her. Though gossip columns have linked her to half of young Hollywood (see sidebar), "nothing ever happened," says the source. The Mayer relationship "is the first time she's dated since Nick."

For now, the couple are simply enjoying a fun, if no-longer-quite-so-private, affair. "It's in the first stages," says the Simpson source. "She realizes it's been very sudden and they haven't known each other really long. But the signals and the emotions seem right."

  • Contributors:
  • K.C. Baker/New York City,
  • Jeffrey Slonim/New York City,
  • Carrie Borzillo-Vrenna/Los Angeles.