The peacock first randomly appears in the used car lot where Milkman and Guitar are hanging out, considering all of the things they will buy and do with the gold they are about to steal. It is completely white, except for a tail "full of jewelry." When Macon first discovers the gold in the cave after killing the man, life, wealth, and security fan before him like a peacock’s tail.
The peacock then becomes closely associated with wealth and with the ways in which wealth can blind people. Peacocks are considered proud, vain creatures that like to preen their ornate tails. The presence of the peacock in the used-car lot seems to foreshadow a disappointing attempt at burglary. Instead of discussing the way in which they are going to go about stealing the gold or the probability of there being any gold at all, the boys are sidetracked and tempted by a discussion of what the gold will bring them. The peacock helps derail their focused, rational approach.