ET's with Jessica Simpson, Usher, Mariah Carey, Donald Trump and Martha Stewart as they serve up a behind-the-scenes look at their new Macy's commercial for a good cause!

"After hours, Macy's employees as well as all of us carrying our [celebrity] brands come together and have a dinner," says Usher of the spirited ad, which also stars Queen Latifah, Tommy Hilfiger and Emeril Lagasse.

It's the newest commerical from Macy's and "Feeding America" for the "Come Together" campaign to help end hunger.

"It's great that Macy's is doing this because it's going to draw attention to the situation and hopefully other people will follow suit," Mariah tells ET.

"Hopefully this commercial will help raise money for 'Feeding America,'" says Jessica. "I think that it's such an incredible charity, and it's amazing when you think about the numbers of how many people are hungry in America."

Click the video for more with the stars, including which legendary figures they'd invite to dinner!