Puppies explore the world with their mouths. Sometimes it seems like they put every single thing in their mouth! You don’t want to accidentally set up a behavior called resource guarding, which is when a dog feels very uncomfortable giving you items they have in their mouth because of the perceived value they might have, so you never want to force a dog to give you something (unless it’s an absolutely emergency). Never hold your puppy’s mouth open or go digging in their mouth. Instead, teach them how to trade (or drop)!
Start by giving your puppy something they want (things like toys, socks, tissue paper, etc). Ask your puppy if they “wanna trade,” and then scatter a bunch of good, high value treats for them to eat. When your puppy drops the item, you can pick it up. After picking it up, give the item back to your puppy, and then trade again!