I'm not really bothered, if I'm honest - it's not as I'll be around to complain. Was at a funeral this afternoon as it happens - don't know how he's being laid to rest.
Didn't they used to bury dead horses under trees to help fertilise them or am I making that up?
I doubt if they ever actually "buried" anything "under" tree. It would be too hard to dig through the roots. More likey they would have buried whatever and then planted a tree over the grave if such was indeed ever practiced.