Funny looking keys.
Chocolate frogs. Cadbury makes them and they are lovely. (Not as cool as the ones in Harry Potter, but CHOCOLATE FROGS!!)
Funny looking coins.
Coins that are actually WORTH something.
Things that are NOT amusing to Americans when the move to the UK:
No electrical outlets in the bathrooms.
Washers and tumble dryers in the kitchen.
No double sinks in the kitchen. (I am sure they exist but have yet to view a property with a double sink)
Coca-cola that doesn't taste like Coca-cola, Dr. Pepper that doesn't taste like Dr. Pepper.
Anyone have anything else they would like to add?