It's hard to find people you trust, especially when you're a celebrity, but Rihanna admits she found that in fellow music superstar Katy Perry, whom she calls "unedited" and down-to-earth. 

The best friends are finally sharing the story about how they became so close — and it all started right before that ill-fated Grammys night in 2009. 

OK! GALLERY: RIHANNA & KATY PERRY ARE PALS IN PARIS 

"[Rihanna] had this cool studded Valentino bag that had sparkly stuff on it," Katy tells the May issue of Elle magazine, which Rihanna covers.

Rihanna was flattered by the compliment and told Katy that she would send her the same bag as a gift. Let's just say, Katy was skeptical. 

"I was like, 'Oh great, here's one of those tricks who talks fast friends but never lives up to it,'" Katy explains. But Rihanna kept her promise! 

"Valentine's Day came around, and I got a little Valentino bag in the mail from her," Katy admits. "I thought, 'Wow this is a woman of her word.'"