Jennie Garth Photog -- She Played 'Do You Know Who I Am' Card

Jennie Garth was DENIED at a hot Hollywood club because she was asked to stand with the common folk, and not because her friends were turned away ... so claims the photog who took the pic.

The photog tells TMZ ... Jennie skipped the line and walked up to the security team at the front door. He says they told her they had no power to make exceptions -- everyone needed to stand in line. The photog says that's when Jennie dropped the card, saying, "I'm 40 years old, I have 3 kids, I've been in the business for years."

FYI -- she's 42.

The photog says the "90210" star did not stand in line, began crying and one of the men she was with tried shielding her from the cameras. She never stood in line ... she just left.