By 1935, the game of Monopoly--including the name--had formed. Two years later, Parker Brothers included die-cast metal player pieces, including a car, a top hat, an iron, a shoe and a thimble, in Monopoly sets. Why? Eddie Deezen asked John Chaneski, an expert on board games:
When Monopoly was first created in the early 1930s, there were no pieces like we know them, so they went to Cracker Jack, which at the time was offering tiny metal tchotchkes, like cars. They used the same molds to make the Monopoly pieces. Game Show sells some antique Cracker Jack prizes and, sure enough, the toy car is exactly the same as the Monopoly car. In fact, there’s also a candlestick, which seems to be the model for the one in Clue. [...]
I think they chose Cracker Jack prizes that symbolize wealth and poverty. The car, top hat, and dog (especially a little terrier like Asta, then famous from “The Thin Man” movie series) were all possessions of the wealthy. The thimble, wheelbarrow, old shoe, and iron were possessions or tools of the poor.