Piled like bricks in stacks a dozen high.
A telling simile. ‘Like bricks’ suggests a weight and substance to Gatsby’s shirts — they are part of a structure Gatsby has built for himself over the five years. He has worked to build up his wealth and status. These outward displays of wealth, these means of disguising/ covering/ dressing his true nature, are in fact the most substantial part of him. The shirts (which Daisy will soon cry ‘stormily’ over) are the foundation upon which he has built his persona.
If we follow this idea further, the fact that he so recklessly dismantles this wall of shirts and hurls them at Daisy could symbolise his willingness to dismantle himself, for Daisy. She evidently picks up on this, on some level, responding with tears. Deep.
To help improve the meaning of these lyrics, visit “The Great Gatsby (Chapter V)” by F. Scott Fitzgerald and leave a comment on the lyrics box