5 year old stealing

[marbles]

What do we do?? He's 5.5, will be 6 inDecember. He just takes things wherever he goes. He convinces himself that it should really be his because he loves it or nobody really wants it or its just trash. He went to the neighbor's porch and took things from under it, he stole a game from the beach house we rented, he takes things from other people's rooms. Buttons, neat boxes, stupid things like a can of tuna, nail clippers, a hot glue stick. I've posted before about how he wants things to be just his, well he will say over and over and over that something was bought for him to get us to agree (we don't) and then he believes it himself and argues that we gave it to him (we didn't!). I have to inspect his bags and pockets when we leave a place to pull out all the things he takes. Sometimes it's stuff he just found on the ground out in public, sometimes it's something he stole. He doesn't seem to see that things belong to people. I'm thinking of emptying his room so I can see everything in it but we have no storage and I dont know where I would put his things in the meantime. It's hard not to think of harsh punishments to spare him from the future we are afraid of.