Lost arcteryx pack/gear lower lee vining campground

At 9:15am on Sunday June 22 my pack fell out of truck leaving campground. Did not notice till an hour later in the meadows. A bike rider saw two guys in camp number 3 or 4 pick it up but they had left by the time I returned at 11:30. I found no note at the entrance, the ranger station or info center in lee vining. If returned I give a $500.00 reward, no questions asked. Super bummed