What is Crooks' American dream in Of Mice and Men?

Crooks is a fairly minor character, but an important one. 
The crux of his involvement in the story comes when George has gone into town with the
boys and Lennie wanders into the barn, into Crooks'
bunkhouse.

The conversation that follows is critical to the
story.  Lennie, given his mental limitations, only knows what he is told about race in
the 1930s, and he doesn't understand it, so he is naturally curious like any young
person would be.  The conversation they have is mostly innocent, and Crooks realizes
that Lennie doesn't know to treat him differently.  For the first time, maybe ever,
Crooks feels like an equal with a white man, even perhaps superior with Lennie.  He gets
to drink a feeling of equality very briefly, until George reappears and sets the
situation how it should be socially, in that time frame.