I think it might be argued that the so-called "dream" or "American dream" in Steinbeck's Of Mice and Men is not George and Lennie's shared dream but really George's dream alone. He has confided his dream to Lennie because he does a lot of talking to Lennie, although his companion doesn't always understand what he is talking about. Lennie is not capable of inventing such a complex dream. In fact, whenever the subject comes up he can only seem to imagine it in terms of having rabbits to feed and fondle. Lennie has to hear George describe it to him, and he believes in it as a potential reality even though George may only regard it as an idea to play with in his mind. George probably does not mention his dream to any other person but Lennie because Lennie is the only person who would share it with him.
George's dream is infectious. First Lennie is infected, then Candy, and finally Crooks. George is the only creative person among them. He is compensating for his dissatisfaction and frustrations by indulging in what he himself knows to be an unrealistic fantasy, a wish fulfillment. The reality seems like a potential nightmare. George would be living in a shack with three severely handicapped men. They would be "land poor." They might have enough food, but they wouldn't have any money to spend on necessities, much less on luxuries. They would need shoes, clothing, tools, and seed in addition to such things as coffee, sugar and flour. It seems like a wretched existence, possibly even worse than George and Lennie are experiencing now. Lennie is dumb enough to believe in it, and Candy and Crooks are desperate enough to believe in it--but does George believe in it himself?
In the 1930s when so many were disenfranchised, separated from their families as they sought work as "bindle stiffs," the men who were itinerant workers yearned for "a piece of the pie," an opportunity for part of the great American Dream.
As Steinbeck's novella opens, George and Lennie, two lonely "bindle stiffs" come to a ranch in the Salinas Valley for work. Before they arrive, the men camp in a clearing by a pool of water, and, as they sit at sunset by their campfire, the childlike Lennie asks the smaller man to relate their dream, the "piece of the pie" that they hope to someday possess.
George's voice became deeper. He repeated his words rhythmically as though he had said them many times before. "Guys like us, that work on ranches, are the loneliest guys in the world....They don't belong no place....They ain't got nothing to look ahead to....With us it ain't like that. We got a future....
"Someday--we're gonna get the jack [money] together and we're gonna have a little house and a couple of acres an' a cow and some pigs and--
"An live off the fatta the lan'," Lennie shouted. "An have rabbits."
The hope of ownership of a farm gives George and Lennie something to work for and to hope for; it is their American Dream, their "piece of the pie." There is much of hope in this dream and some of religious fervor in this deep, rhythmic recital. Moreover, it inspires hope in the hearts of others such as the time-worn Candy and the marginalized Crooks. For, when contemplating the idea of sharing, both men are revitalized.
That these men are revitalized by their hopes of the future is evinced with the death of Lennie, the man-child who has kept alive this impractical goal and made it seem possible with optimism that only an innocent can possess. For, once Lennie dies, so, too, does the American dream of the other men. As they stand over Curley's wife's limp body, George tells Candy,
"--I think I knowed from the very first. I think I knowed we'd never do her. He usta like to hear about it so much I got thinking maybe we would."
Their dream of a "piece of the pie" in America gives Lennie and George hope for a better life in the future.