At my school, I purchased my cap but rented the gown. The cap is in a box never to be looked at again. I can't imagine what I would do with the gown.
Marriages, graduations and funerals carry forward some traditions that haven’t made sense for generations. They are the irregular verbs of modern life. Interestingly, marriages and funerals often have a religious element, and religion itself is conservative—but graduation doesn’t have that excuse.