So I've been completely going through a new to me H2 for the past couple weeks. All the leaks finally fixed and working on the body. While my existing thread is at https://www.hummerforums.com/forum/hummer-h2-8/completed-major-maintenance-new-me-hummer-h2-47958/page4/#post407640

.... I thought maybe sending these photos out in a separate thread might yield some answers. I was replacing the cables under the second row seat, and removing the rest and getting the third row functioning when I stumbled upon these two pieces under the second row seat. One appears to snap in place covering a seat mounting bolt, but I don't appear to be missing any. Not sure what the metal piece is all about. Would appreciate if anyone can help identify them

 

I believe the metal one is part of the jack mounting that helps hold it down and prevent rattling. The other is as you say, a trim cover for some bracket or seat track somewhere.

 

Thank you, I hadn't thought about the hardware for the jack. My Jack is there mounted behind the second row seat but all the tools are gone.

 

Not part of the toolkit. The toolkit is just jack rod and such. It does look like spring steel, and as such, possibly some sort of anti rattle or tension spring. The foam on one side of it also suggests that.

Not a part of my 07 jack hold down either, unless mine is gone too.