I can only say that DS (now 14 ASD with LD) was doing exactly the same - 'finding' money. Actually he is incredibly good at finding dropped money,(because he is so interested in money) but I am more concerned about 'finding' money in my or others purse or pocket. Eventually he has learnt that this is stealing, but it has taken some time to get him to understand that what is in my purse/bag/ pocket is mine. He has a what is yours is mine but what is mine's my own attitude, especially with family things! Because of his learning disability he is not good at hiding things so it has been easier to see the reasoning behind his stealing. I still have to be very careful. He does not understand about budgeting and making money last. I used to say I did not have enough money to buy him (insert most desirable item on earth at that moment for ds), but later he would sneak into my purse and consider it a lie if he found money in there. He would be angry and take it! Once he took a £20 note to school to the tuckshop - fortunately the teacher in charge of the shop (who knew of our concerns - its a sn school) got the truth out of him and sent the money home again. I have been trying to show him what we need money for - mum's train to work, so I can earn my pay, petrol for the car so Dad can get to work etc. He likes to treat his classmates from the tuck shop if he 'finds' money - he has trouble with friendships, so it buys him popularity. I think also he sees treats as a reward for being good, so wants treats to feel worthy IYSWIM. All rather sad. I agree with getting help to get to the bottom of it.