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Selena Gomez on the set of her Fall 2010 ad campaign. Photo: Albert Michael, Startracksphoto.com

Selena Gomez's new collection for Kmart, Dream Out Loud, has a definite American style, but her back-to-school photo shoot was strictly an international affair.

The pictures were taken back in May on a hillside farm outside Budapest, where Gomez was filming "Ramona and Beezus," which is set to be released July 23, and the models were flown in from London.

And just like a typical teenager, Gomez -- who turns 18 later this month -- arrived on set at 7am (accompanied by mom), wearing a track suit, her hair all over the place, carrying a bag of McDonald's, and a huge Diet Coke, Kmart's chief marketing officer Mark Snyder told StyleList exclusively.

Once settled, Gomez was all business. "Selena plugged her personal iPod into the speaker system and chose the music for every shot," Snyder said.

"She started with Taylor Swift, and ended the day with Cyndi Lauper's 'Girls Just Wanna Have Fun.'"

He continued: "Selena was very engaged with the shots themselves and stepped into the tent where we were viewing actual shots on-screen with the photographer and myself to agree on what shots looked best."

The food was a far cry from McDonald's. "Lunch was strictly Hungarian fare," Snyder told us, and Gomez and all her new model friends retreated to her trailer to listen to music.

Later the whole cast and crew enjoyed dinner together at an Indian restaurant before flying back to their respective countries.

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The gang's all here! Gomez with her circle of model friends. Photo: Albert Michael, Startracksphoto.com

By then, "they were all fast friends and carrying on as those they had grown up together," Snyder added.

Dream Out Loud by Selena Gomez hits Kmart stores later this month.

For more celebrity fashion lines, check out Britney Spears modeling her Candie's collection.