It's been 15 years since Carrie Underwood officially became a Grand Ole Opry member on May 10, 2008, and she marked the occasion with two special shows on Saturday night (May 13.)

Backstage, the Opry recognized Underwood's milestone with a nine-tier cupcake cake, topped with two tiers of full cake that read "15" and "Carrie." The singer also received a plaque to commemorate the anniversary.

But perhaps the most special gift of all was a bouquet of flowers from the singer's fans, who go by "the CareBears," and who also made a $250 donation to Underwood's C.A.T.S. foundation in honor of the anniversary. The C.A.T.S. foundation benefits causes in Underwood's hometown of Checotah, Okla., including providing resources for the public school system, furnishing playground equipment and establishing a pet shelter that emphasizes a spay and neuter program.

After the festivities concluded, Underwood hopped on social media to post a carousel of photos from the special night and express her gratitude to all those who acknowledged and celebrated the milestone.

"Happy anniversary to me!!!!" she wrote. "It's been a magical 15 years of being an [Opry] member! It remains one of the greatest accomplishments of my career!!!! Thanks to all who came out to celebrate! I truly feel honored...and loved!"

Among the photos Underwood posted were a couple of snapshots of herself and the stars in attendance at the Grand Ole Opry that night, including Deana Carter and actor Susan Lucci, the latter of whom Underwood met that night for the very first time. "What a sweet and gorgeous (and legendary) woman!" The singer commented.

Underwood shot to fame after winning American Idol in May 2005, and she made her Opry debut just weeks afterward, on June 10. She became a regular performer on the stage, and three years later, in March 2008, Randy Travis surprised her during an Opry performance with an invitation to become a member.

Garth Brooks -- a fellow Oklahoman -- was the one to formally induct Underwood during her May 2008 ceremony, and she kissed her trophy after he presented it to her. That night, she performed some of the biggest hits in her catalog thus far -- "Last Name," "All-American Girl" and "Jesus, Take the Wheel" -- and tearfully offered her appreciation at being included as part of the Opry family.

"It means a lot to me. I promise that I'll do everything I possibly can to make you not regret it — and to make you guys not regret it!" she added, addressing the audience.

Most recently, Underwood has continued to be a regular performer on the Opry stage in between stops on her recently-wrapped Denim & Rhinestones Tour and her Reflection: Las Vegas residency, the latter of which will pick up again later in 2023. Underwood's next planned Opry show will take place on June 6 as part of the "unofficial kick-off party" for CMA Fest 2023.

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