Most artwork depicting Roland at the Tower shows him wearing a hat. We know he had one in the early stages of his journey, but I can find absolutely no mention of a hat in the final book.
The clothing he is wearing at the Tower is what he and Susannah made out of deerskin: leggings, vest, coat (with hood, presumably) and leather mittens.
The following quotes from DT7 lead me to believe he doesn't have a hat any more.
"Beyond the circle of the dying fire a wind moaned, lifting Roland's hair from his temples"
"He brushed his hair back from his forehead, leaving a fresh smear and now making her think of penitents on Ash Wednesday."
After they reach the Tower, Patrick "took the sides of the gunslinger's head in his hands and brought it forward until they were brow to brow."
Hard to do if he's wearing a cowboy hat.
Thoughts?