On what page in Of Mice and Men is Crooks talking about his dream?

Crooks dreams of having company and belonging somewhere where he is wanted.

Crooks wants to belong.  He is the African-American stable hand.  Because of his race, he is ostracized by the ranch hands.  They do not want to associate with him.  While most of them are migrants, he has been at the ranch for a while.  He has his own room, because he is not allowed in the bunkhouse, but it is really just a corner of the harness room. 

"Why ain't you wanted?" Lennie asked.

"'Cause I'm black. They play cards in there, but I can't play

because I'm black. They say I stink. Well, I tell you, you all of you stink to me." (Ch. 4, p. 68)

Although he initially tells Lennie to stay away, Crooks invites him in because of his “disarming smile.”  When Lennie tells him about his, George, and Candy’s dream to have their own land, Crooks tells Lennie about his childhood when he was treated better by whites because his father had land. 

Crooks explains to Lennie that he is lonely.  He is jealous of the fact that Lennie has George to travel around with.

A guy sets alone out here at night, maybe readin' books or thinkin' or stuff like that. Sometimes he gets thinkin', an' he got nothing to tell him what's so an' what ain't so. Maybe if he sees somethin', he don't know whether it's right or not. He can't turn to some other guy and ast him if he sees it too. (Ch. 4, p. 73) 

Crooks tells Lennie that land is like Heaven.  Everyone who comes through the ranch wants a little piece of land, and no one ever gets it.  Candy comes in, and Crooks tells them that they are both kidding themselves.  He is surprised to learn that Candy has some money put away. 

When the dream seems possible, Crooks wants to get involved in it. 

"...If you... guys would want a hand to work for nothing- just his keep, why I'd come an' lend a hand. I ain't so crippled I can't work like a son-of-a-bitch if I want to." (Ch. 4, p. 76) 

Crooks says he has seen people go crazy for a little bit of land.  Things take a bitter turn when Curley’s wife comes in and makes trouble.  In the face of her racism, Crooks is reduced to a man with no personality, and tells them he is not interested.  The dream is just that again—an impossible dream.