Selena Gomez -- Mom, Look Who I Brought Home For Xmas ... Cara Delevingne!

Selena Gomez brought home a new friend to meet the parents in Texas ... one Cara Delevingne!

Selena and Cara became fast friends this summer. We first saw them on a yacht in St. Tropez where they celebrated Selena's birthday and showered down together.

Fast forward to this week ... Selena went to her parents home outside Dallas for XMAS, and brought along Cara.

Selena and Cara hit up North Park Mall in Dallas, where they paraded around Victoria's Secret ... where they shopped for bras. They then made a beeline for Nordstrom, where they held hands and Cara slapped Selena's ass.

Justin who?