Who is Mr. and Mrs. Larsen from Shaking the Nickel Bush and what is their importance?

Mr. and Mrs. Larsen own a restaurant in Phoenix. They befriend Ralph and care for him while he is there, especially after learning about his special diet. When Ralph buys the car, Mr. Larsen helps him figure out how to repair the engine on the car. They then give Ralph and Lonnie a supply of groceries and other necessities to help them survive while they are on the road.