in this crime scene photo it really looks like a pair of white sunglasses next to the bag. look and see if you think so too....
http://www.rsxtaci.com/Caylee/196482.jpg
I can't even see the bag. I see a large brownish/black object which looks like part of a fallen decayed tree trunk laying sideways. If that is what you are making out to be the bag, LE would not have put the pole of the tent over that area I would guess. I would think the tent is centered over the evidence, IMO, the tree in the foreground (with vine growing on it), blocks the view of any bag on the ground in this pic.
Casey was wearing a pair of white sunglasses (bought with Amy's stolen check) at Target and later seen wearing to her attorney's office.