We had fun shopping for our friend's daughter, the eldest that Bruce entertained in Portland, at the Harry Potter shop.  It is called THE SHOP THAT MUST NOT BE NAMED .  We got the 5 year old a t-shi3that says "I solemly swear I am up to no good,  Harry Potter" It is written in gothic script.  We purchased 2 items for each of them, small enough to fit in our full carry-on bags.
The employees were extremely helful.