Credit: Splash News Online

Teen Mom's Maci Bookout and new beau Kyle King packed on the PDA at a pumpkin patch in L.A. Monday.

"They were having a great time running around the patch," a witness tells of their 20-minute visit.

Nineteen-year-old Maci -- who has a 23-month-old son, Bentley, with ex, Ryan Edwards -- "was picking up the biggest pumpkins she could find," the onloooker tells Us. "She would use all of her strength to stand up. They were so heavy they almost made her topple over! Kyle was laughing at her."

It wasn't all joking around.

At one point, Kyle "came over and kissed her," the witness adds. "It was a cute couple-y thing to do. They were flirting and holding hands. He was really sweet and attentive the whole time."

When Maci went over to a giant wooden pumpkin and stuck her head through the cutout, Kyle snapped a photo. Adds the onlooker, "It looked like they were having a great time."