The easiest way to deal with this is to start from puppyhood. Get your dog used to having you come and take his things away. Give them back, but take them for a while. Let him see that even someone else has something he wants, if he waits patiently he'll most likely get it back.
Teaching a "give" command will also help. When your dog has a toy in his mouth, gently take it from him, saying "give" at the same time. When you have it, reward him and praise lavishly. By rewarding him as well, he'll learn that to give something to you, means to get something even better at times.
Introduction to Canine Mental Health
Do Dogs Get Depression?
When Anxiety Attacks[]
Biting the Hands That Feed You
Obsessive Compulsive Behaviors
Physical Issues
