Tom is associated with a few different items across the novel.
The most salient and personal item is his cap. Tom begins the novel with a new cap and shapes the cap brim as the novel moves along.Tom uses the cap to wipe his face as well. This is the most repeatedly mentioned piece of clothing in the text. Casy even asks Tom where his cap is late in the novel when the two men meet again after being separated for a month.
Tom is also associated with a pick ax (which he is handy with and which he uses to hit the man who kills Casy).