Inside Taylor Swift & Travis Kelce's Wedding: Adam Sandler Sings, Jason's Kids Throw Flowers & More

Adam Sandler made Taylor Swift and Travis Kelce's wedding ceremony unforgettable ... singing them an original song as he served as their officiant, TMZ has learned.

Sources with direct knowledge tell us the song Adam wrote for the bride and groom was humorous yet touching and was all about their love.

The ceremony took place inside New York City's Madison Square Garden Friday, and we're told it was held a level up from the ground floor, where there was live music with strings. Adam was the first person to come out, and Jason and Kylie Kelce's kids were the flower girls, who threw petals around Taylor as she walked down the aisle.

Taylor walked down the aisle to one of her songs being played on strings, our eyewitness tells us.

As we told you, Taylor and Travis wore custom Christian Dior Haute Couture designs, and Travis opted for a white tux, according to our sources. We're told Taylor had a long gown with a train.

At the end of the ceremony, Taylor's mother, Andrea, invited attendees to join them at the party downstairs on the main floor. Our source describes the decor as "Alice in Wonderland" meets "The Wizard of Oz." Remember, we already told you there was a greenhouse structure built and even a garden to welcome guests.

Our eyewitness says there were tons of food catered by one of the superstar's favorite NYC joints, Zero Bond. We know Taylor visited Zero Bond just a few weeks ago to celebrate the Knicks' Game 4 win in the NBA Finals. She also made sure guests were entertained with carnival-like games.

We already saw tons of Taylor and Travis' A-list guests heading to MSG for the big soiree ... but TMZ has learned of even more attendees: Jennifer Lopez, Tim McGraw, Faith Hill, Tom Cruise, Gwen Stefani and Blake Shelton, Reese Witherspoon, Paul McCartney, the Haim sisters and Stevie Nicks.

Our source left before any surprise artists took the stage ... but they had a hunch Paul, Stevie, and HAIM were getting ready to sing some songs for the lovebirds.