Another children's (?) book ID

Second grade. The story involves a young refugee from Europe after WWII travelling across America. I don’t remember how he got to the U.S., nor where he was going He meets a character named ‘Dud’, and the teacher who was reading it to us always mispronounced it ‘Dude’. The other thing I remember is when he received something ‘for free’, and the character made a mental note that in American things gratis are ‘for free’ instead of just ‘free’.