Any suggestions to stop this?

Some puppies are like that. If I had a dollar for every stone I took out of my dog's mouth when she was a puppy, I'd be rich. Today she wouldn't dream of picking one up, not because she's not allowed to, but because it doesn't even enter her mind to do so.

Teach the puppy "leave it", and try to stop him as soon as he even thinks of taking something. If you have to take something out of his mouth, exchange it with a treat to prevent future resource aggression.

Try teaching him the trick leave it, this can be done by starting with a treat and putting him in a sit position, after that is done show him the treat and say leave it. When that is done place the treat on the ground, if he leaves it say good leave it then reward him with another treat, NOT the treat that you told him to leave. If tries to eat the treat, say "Ah-Ah" in a louder tone then pick up the treat and try again. If he picks up the treat in his mouth you will have to dig it out.

This isn't something you should worry about, but you could see a dog behaviourist to eliminate the problem. Or you can just train him to ignore them. When my dogs smell at something or bites at something, I tell it, let's go, come on! And you could try this too and hopefully it will get the whole trick.

This may be due to a condition called Pica. You need to tell the vet about it and have the dog examined, see what the vet can do.

It could just be a puppy thing but i would double-check with a vet, just to be sure.

P.S. He sounds so cute! Bless him

Bring to see doctor