If you look at greed, as not just the desire for possessions, but as the unharnessed desire for anything, then greed appears as early as scene 3 of Act 1 when Macbeth finds out he's been named the Thane of Cawdor as the witches predicted and he wonders if he'll become king as they also predicted. He hungers for the crown when he begins his "Two truths are told..." aside (ll. 148-163). Act 1, sc. 4 shows greed when Macbeth hears that Malcolm has been named the crown prince and Macbeth realizes that action will either stop him from becoming king or make him do something about it ( ll. 55-61). Greed also appears in scene 5 of Act 1, when Lady Macbeth receives her husband's letter telling her about what has gone on with the witches and his new title. If we continue to equate greed with runaway ambition, then greed shows itself in the last scene of Act 1 as well. Act 3 displays the them of greed as well. At the beginning of the scene when Banquo is talking, he speaks of all that Macbeth now has. Later in the scene, when Macbeth speaks to the murderers, he tries to convince them that Banquo was to blame for their lack of fortune (ll. 80-90). Greed is mentioned in Act 4, sc. 3 when Malcolm is testing Macduff's loyalty by saying that he, Malcolm, would be a terrible king because he had so many faults, including greed (ll. 69-78 and ll. 106-115).