The “Pieces of Me” songstress and her “90210” gal pal hit up the West Hollywood hot spot to see John Mayer perform one of his well-known surprise gigs.

And as they left the venue, both Ashlee and Shenae looked like they’d just witness a killer show thanks to the “Your Body is a Wonderland” crooner.

“He’s the nephew of the guy that Annie hit, and you get to see how he encompasses himself into the relationships of Beverly Hills,”

Tristan Wilds tells us.

Want to know who it is in particular he’s getting close to? We have the exclusive details from the castmembers themselves…

“He’s totally that Christian Slater in Heathers kind of vibe—that creepy older dude who you just can’t take your eyes off of,” Shenae tells us. “I have a bad feeling in my gut, and I think he’s going to take Annie for a little bit of a spin.” Their new friendship may turn a little personal, though: “She thinks she finds love and that may screw her up a little more,”

So does Jasper know that Annie killed his uncle? Shenae spills,

“My gut instinct is that he may [know I killed his uncle], but Annie hasn’t told anybody. It’s definitely a secret right now.”

On the new casting of Zachary, she adds,

“He is a phenomenal actor, and I’m so excited to be working with him.”

A few of the West Beverly kids may question Jasper’s motives, though. Jessica Stroup tells us,

“Is he a manipulative person, or is he someone who’s really honest about what he’s saying?”

(We can’t wait to find out!)

Grimes, 19, says playing Annie Wilson has been a real roller-coaster ride.

“Annie was raised with Kansas values with a very close-knit relationship with her family,” she said, “and then some drama went down last season. This year she’s going through the teen angsty stuff I went through a few years back. We’ve all had those bratty moments. But hopefully I can bring some wisdom to the character and do it with a sense of realism.”

You can check out Season 1 of “90210? on DVD, on sale this week. But first, check out her weekend.

The great outdoors

In the afternoons, I like taking some time out to have a nice cup of tea while I’m sitting outdoors somewhere like the Urth Caffé. It’s very relaxing to be out on the patio. Green tea is probably my favorite, but I love the fruity ones too.

After that, I’d go to a movie screening at the Hollywood Forever Cemetery. I’d just pack a picnic dinner and make a night of it. I’ve never been there, but we filmed an episode of the show where we went there and saw “Psycho,” and now I’ve just got to make it happen in real life. I love movies, and I have a list on my BlackBerry of some of the older movies that I want to see. I just think I’d enjoy a low-key night like that where I could actually chat with the person I’m with and still enjoy a good movie and a nice meal.

Toast of the town

I love the menu at Toast. It’s pretty crazy there on weekends, but if you can get a seat, the food is awesome. They have everything you could want — omelets, pancakes, waffles, fruit and granola, anything your taste buds could desire. It’s so quality and delicious. I’ll usually get fruit with granola and yogurt and sweet potato fries and possibly some eggs. It’s very homey and cottage-y inside.

Another great thing to do is take friends from Canada on a hike up into Runyon Canyon. It’s not too exhausting; I always see all these little dogs along the hike and I think, “If that little puppy can do it, so can I!” And from the trail there’s a beautiful view of the whole city and the Hollywood sign. Canadians love to see that sign.

After that I’d go home and take a shower for everyone’s benefit, and then go out for sushi. I like Matsuhisa. It’s got really quality sushi and is definitely a fine-dining restaurant, but it’s still very homey with service that’s always friendly. I don’t like the hoity-toity fancy places because it intimidates me.

After that, I usually just go home. I’m still underage, and I’m not one of those actresses who tries to sneak into clubs. You get caught or you get into trouble, and it’s just not worth it. I might go to Pinkberry instead. I’m addicted to Pinkberry — there, I said it. I like the mochi topped with mango.

The water’s fine

On Sunday morning, I’d drag a friend to yoga and then to the beach. I just love it there, and the fact that it’s almost always good beach weather. The one beach we had in Toronto was dirty and I don’t think you were allowed to go into the water because you probably would have grown a third arm. And the weather can be pretty chaotic, too. Here, it’s just wonderful. I like the Venice boardwalk because of all the characters you find. And there’s always great snacky foods around.

And then there’s the Melrose-Fairfax flea market. I furnished a large part of my apartment by getting some great deals there, and they also have unique clothes. And there’s a fruit market on Melrose Place that’s really good, too.

On Sunday night, I’d have friends over and maybe they’d be so daring as to let me cook for them, or maybe we’d just order in from Chin Chin, where they have this amazing to-go salad. And they dip their fortune cookies in chocolate, so it’s a nice little treat.