Abby does this all the time! She buries food and certain treats, I think at least, to save them for later.
She use to roll things with her nose into every single corner of the house she could access, and cover them with "invisible" dirt. Then, she got more inventive and started burying things in places like between my daughter's dresser and toy box, which she covered with a pair of socks, and in beds which she covered with blankets...imagine finding a half eaten, mushy, drool covered bone in your bed

ukey:
One time, just recently, I gave her a small, roundish treat and had one of those "What the....?!?!" moments when I came across it "buried" somewhere and couldn't figure out what it was right away. I picked it up, put it in her bowl and right away she picked it out and buried in the EXACT same spot, again. :lol2:
I am pretty sure she is not trying to dispose of them, because if she finds something she doesn't want to eat in her bowl she picks it out of the bowl and drops it on the floor.