Long, sorry!!!
My ds is 4yrs 9 months and obsessed with taking things to childcare. They do not allow children to take things from home or toys etc for obvious reasons of jealousy/broken/losing etc. I have explained this to him as best I know how, but he keeps sneaking things into his pockets and bag without me knowing. Each time I pick him up his teacher has another thing to give me that I didn't know he had. Yesterday was his sister's necklace, a kitchen clip and a pair of nail scissors from the nappy bag!!! This has been going on for months and I have got to the point of checking his things before we leave yet he still gets it in without me knowing. He says he wants show and tell and I get him things for that (bugs from garden etc) but have tried to tell him he can't have show and tell everyday. I also had teacher explain all this.
This has also extended to pocketing things from my dd's classroom (piece of puzzle or chalk), toy from a friend's house etc, clothes tags from shops etc etc etc etc. I don't know what to do. I don't know how to punish him, I don't know if he understands "stealing" and "lying", is this a phase or will I see him in prison in 15 years????