The "Nashville" star told Ellen about her misadventures getting to the White House Correspondents' Dinner -- and who she confronted on the red carpet. 

"Best/worst day of my life," she said. "I can't even explain it. I woke up with a scratched cornea, I don't even know how I did it... all of the sudden I couldn't see out of one eye." 

Hayden grabbed some chamomile tea bags to place on her lids and took a nap, thinking the tea would alleviate the pain. The result? Her eyes had swollen shut -- she was allergic to chamomile! 

"I almost went with an eye patch," she said, revealing a photo. "We were thinking about blinging out an eye patch." 

Then, a few hours later and with the help of a makeup artist -- she managed to get red carpet-ready. The only problem now? "The other dress broke, it was a beautiful disaster." 

Thankfully, she slipped into a yellow number -- and ran into none other than Bill O'Reilly. The two have had an interesting relationship since Bill called her a "pinhead" on national television. She decided to confront him. 

"I said, you called me a twit, what's that thing that you call people, a pinhead... because of my environmental work?" and he went, "Oh... I'm sorry." 

"I said, 'No, it was the biggest compliment in the world that I said something important enough for you to call me a pinhead.' And then the next day on the show, I kept getting tweets that he had retracted my pinhead status." 

What a day.