John Reed proposed to Rebecca in Perdido Key Beach, Florida, and the 27-year-old reality star filled ET in on just how the sweet seaside surprise went down at her husband-to-be family's condo.
"We go pretty often, and one of our favorite things to do at the beach is to go treasure hunting -- aka looking for shells, and we keep score, too! -- so we went on what I thought was our typical treasure hunt around sunset," she told ET, adding that the afternoon was chilly but beautiful. "I was determined to find the best shell that day! We had been walking for about an hour, and I saw this beautiful swirly shell hidden in the sand -- and the ring was also hiding in there!"
"He got on his one knee, pulled the ring out and said, 'I wanna spend the rest of my life with you. Will you spend the rest of your life with me?'" she continued. "Then I said yes! I cried, and he said he teared up 'a little.'"
Rebecca had no idea the proposal was going to happen. "Apparently all my friends and family knew, but everyone did a really good job hiding it from me," she said. "They have got some really good acting skills!"
She also admitted that at first, she thought the shell was fake "because it was so pretty and crazy looking" or even possibly a Christmas ornament that had blown onto the beach. "I almost threw it back in the sand -- that would have been bad!" she said.
On Friday, Rebecca posted an adorable scrapbook doodle of the proposal to Instagram, complete with "I'm [the] future Mrs. Loflin," "OMG" spelled out with a diamond ring and "2016 our story starts here."
She also shared a sweet photo of herself kissing a crown-wearing John Reed, as well as a good view of her unique new Art Deco ring!
"After long time of patiently searching, I found the ultimate gem // Jeremiah 29:11," Rebecca captioned it.
The 14-karat gold band was designed by Nicki Loflin Sampognaro and features a large oval-shaped opal -- Rebecca's favorite stone as well as her birthstone -- surrounded by gray pave and baguette diamonds.
Rebecca's little sister, 18-year-old Sadie Robertson, excitedly shared her own sweet photo of the pair on Instagram. "MY SISTER IS GETTING MARRIED TO HER BEST FRIEND!!!! I'm so happy for you Rebecca," she captioned the adorable pic. "John Reed... good luck joining our crazy family. So excited for y'all to began y'alls journey of life together. 1.1.16."
Rebecca -- who was born in Taiwan and now runs the flagship Duck & Dressing store in Monroe, Louisiana -- joined the Robertson family in 2004 at age 16 after coming to the United States as a foreign exchange student. Now she is Willie and Korie Robertson's foster daughter and one of the couple's five children. She met John Reed on Halloween at the 2014 Voodoo Fest in New Orleans, and the two have been together ever since.
Korie has happily started celebrating, prepping a Sunday night engagement dinner of crawfish pies, shrimp au gratin and grits.
This will be the first marriage for Rebecca and second for John Reed, who split from his ex-wife last year.
Now, Rebecca is thrilled to start planning what she hopes will be a destination wedding. "We are beyond happy and thankful for our family for leading up to this chapter of our lives, and we are so excited to see what God has in store for our future," she told ET. "We want to spread love and kindness all over the world together."
It looks they'll be plenty to talk about when the new season of Duck Dynasty premieres on A&E on Jan. 13!
Rebecca's younger brother, John Luke Robertson, got married last June. Find out all about his nuptials to Mary Kate McEacharn in the video below.