Now here's what Bud and Bugs were actually given. Sardines are little fish that come in cans like you see first. After the fish are gone, the cans were re-used as bowls, like the second picture. Would you call this "fine china"? Why would the people of Hooverville call them "fine china"?
So what's a mouth organ anyway? One person (actually from yesterday's reading) is called mouth organ man. Well, here it is:
Finally, what are "Commies"? The police officers say the men wanting to board the train sound like Commies. The simplest way to describe it is this: Commies is short for Communists. Communism is a form of government very different from the United States government, and many of the United States enemies have been Communist countries. In a situation like what we read in the book, calling someone a Commie was an insult, like saying someone was anti-American. It would be like saying, "What? Are you saying you hate the United States of America?"