Harris, who tied the knot with Hefner over on New Year's Eve, has decided to honour Mary O'Connor, the adult magazine mogul's secretary of more than 40 years, by raising money for a good cause, reported E! online.
The 26-year-old blonde beauty is selling off the pink gown and shoes she wore when she exchanged vows with Hefner, 86, on December 31, via an auction on Charitybuzz.Com.
"I am auctioning my wedding dress... To raise money for lymphoma in memory of Mary," Harris posted on Twitter.
A message posted on the auction website states, "Crystal is donating this dress in memory of her good friend, Mary O'Connor. Mary was Hugh Hefner's longtime assistant of 40 years, and is credited with helping Crystal reconcile with Hef last year, ultimately leading to their recent wedding. Money raised will benefit the Leukemia and Lymphoma Society in Mary's name."
The auction ends on February 11.