The Beckham's say they don't know what to get Tom and Katie for a wedding gift...

neither does Oprah.

(People)What do you get for two glamorous movie stars like Tom Cruise and Katie Holmes for their wedding? That's the question that David and Victoria Beckham are still trying to answer, a source close to the couple tells PEOPLE. "David and Victoria are still scratching their heads as to what is the perfect present to give them," says the source. "It's pretty damn hard finding the ideal gift for Tom and Katie." After all, the star couple are having a fairytale wedding – which will reportedly take place at the Castle Odescalchi outside Rome amid friends and family, including their daughter, Suri, and Cruise's two children from his marriage to Nicole Kidman, Connor, 11, and Isabella, 13. Another item still up for consideration for Victoria Beckham – what to wear to the black-tie ceremony. The fashionable former Spice Girl is still choosing between six or seven outfits for the nuptials, the source tells PEOPLE. The Beckhams aren't the only ones stumped about what to get the couple who has everything: Oprah Winfrey, who was not invited to the couple's wedding, doesn't know what to get for Cruise and Holmes either. "I'm easier (to shop for) – you can get me a bubble bath I'm okay – but I don't know what to give them," she said.