Not the fold down seat I checked that and my wife reported noise is still there today after I folded the seat down yesterday.
I am thinking control arm bushing, sway bar bushing or sway bar link. I will be checking it out tonight. I will try to shoot some silicone spray into these areas and see if that makes a difference.
I could definately feel the vibration in the spring/control arm area when the left corner was bounced. Also it is specific to the drivers side, no noise on the passenger side.