Mine all "drop" when requested, even bones - because they have been trained to, and if I needed to remove say a Kentucky fried carcass from their gobs I could do, forcibly, without them biting me - because I know that they aren't threatened by me fiddling with their mouths.... however, when we first got Barley, and Gracie, I would never have been able to - because they were very very "guardy" about their food, understandably.
So I taught them it was ok to eat bones around me, because I wasn't going to take stuff away from them, in fact, I was going to GIVE them stuff when I went near them. Soon, Barley started to wag his tail when I went near him, as opposed to the initial growling when we first got him...
Some dogs guard, some don't - naturally. Honey, as I understand it, has always guarded from a youngster, and it only takes a few wrong moves to make them guard more. She is very clearly saying by growling and wagging her tail at the same time "look , I do like you, but please leave my bone alone, it's MY bone, and I want to keep it, and I'm sorry to growl at you"...