You know, if I was going to bury something, it would be something I needed to come back and get. Something I couldn't replace or needed to hid and get back later. She got rid of so much evidence and the body at the Suburban site, this was something she wanted to keep, it was small enough to bury under those slabs and needed to hid so she wouldn't get caught with it. My guess is the phone, journal, photos, or a set of keys. Cloths are too bulky to bury in a bag and you have to dig a little deeper, she was lazy, she didn't even bury Caylee.