
My two year old girl Opi does it every now and then - usually with bones (natural and the white rawhide type). She's not very good at it though - the last one she "buried" on the sofa by nosing dog hair over it :) and before that, she buried a rawhide bone in the 4" gravel-filled gap at the back of our patio! I saw a pile of gravel, and was most perplexed until I saw her nosing more gravel onto it, then it clicked what she was doing :D The first time she did it she buried one of those sterile stuffed bones, de-stuffed, under a small table (one of the foot suqare nest-of-table ones), and covered it with a huge pile of dog hair! Not nice, and she'd chewed it a bit so it all stuck!
My other dog doesn't do it, nor does my brother's, and my old spaniel X didn't do it. Very much an individual thing :) Opi's a nutter as well, which helps I think!