Yes, my dog is a resource guarder and was pretty much from day 1 of getting him. We have managed things by making sure he doesn't generally have access to the items he guards. This can also be tricky as these are the things that engage and entertain him, so admittedly, on certain occasions he is still allowed bones when we are pretty sure he will be completely undisturbed in the kitchen behind a baby gate. But then we would go through a set procedure to distract him by calling him to another room for food and separate him from the bone before throwing it away so that no guarding behaviour is evoked and he doesn't notice. We can see that actually, having items that he guards is a huge burden/ stressor to him, especially when he is tired... it's like he is thinking 'O I really want to go to sleep, but that bone is there, and if I don't guard it my whole world will collapse!' He is much happier when he is relieved of it after an hour or so of enjoying it.
With a dog that guards anything that can be a bit harder to see a hierarchy of value that we can clearly see with Ollie. It is generally considered very impolite in the dog world to take anything out of their mouths - possession is ten tenths of the law to them(!), so I wouldn't be trying to correct him by trying to compel him to let go of whatever he has found - this will elevate the value of the item in his mind 'o well, if she wants it, I must have found something really good this time!' The best way is to act like you couldn't care less what he has taken and then he will attribute less significance to it. That, or perhaps swapping for treats..but this is something you may have to build up to depending on the level of his response... ideally you want to keep it below threshold, so if he starts tensing and sideways glancing when you are 2 meters away, then you should start throwing him treats from 3m away. Gradually over time building up closeness as he associates your presence with nice treats and begins to welcome it and keeping it under threshold of response, so that you can get closer and closer, sit next to him ad eventually swap what he is guarding for a treat- before giving what ever it is he is guarding right back again. That way you build up trust..but it is important to not push things too fast. This positive approach does often work well.
You can try that approach, and I think that is what the Mine book details in more rigour. But to be honest sometimes they just need a break from the whole process and experience of guarding - we tried to test Ollie with this sort of approach and you are always in danger of reinforcing a guarding approach if you get it wrong or move too quickly..so whilst I would say use that approach if he already does have something he is guarding, don't go out of your way to contrive a situation regularly to test him as this can lead him to more stress and make the guarding more of a learned habit for him.
I would say don't get worked up about it or become angry, frustrated or forceful in your approach as this can escalate the situation and make an already tense dog snap. Try to get everyone who lives with the dog on the same page, and especially around a young child try to manage the situation. I really sympathise with you and anyone else going through this with kids as I've said on this forum before. Try to raise your child's awareness of when the dog is uncomfortable - think about the body language and the signs they give off, and stress to them they must not go near the dog in those situations.
It sounds like your dog has taken to a particular corner, so you can perhaps try to rearrange the furniture so that he does not access it in the same way to guard. That might help to disrupt his habit...but it is very possible he will just start doing it elsewhere. A behaviourist who sees your dog, setup, family and interactions will be best placed to help you.
