Manley, 50, apparently inhaled the 1-inch plastic fragment while eating at a Wendy's restaurant. The Wendy's logo can still be seen on the side of the plastic.
"My assistants that were working with me started spelling out these letters," said Dr. Momen Wahidi, a pulmonologist at Duke University in Durham, N.C. "They started making out that there was an A-M-B. We eventually realized that this was a hamburger, the word 'hamburger.' This was a surprise to all of us."
Manley doesn't remember feeling anything but said he does have a habit of wolfing down his food.
"I'd go in there and eat quickly and take bigger bites," he said. "I came from a big family. You eat fast if you want your food."
Doctors removed the plastic from Manley's left lung last week, and he is expected to make a full recovery.
"Watching him on the lawn mower, which John loves, is fantastic," wife Karen Manley said.
Manley and his wife did not understand his sudden coughing fits and fatigue after they moved to North Carolina from New York City two years ago.
"I put myself in a hospital because I was spitting up blood," Manley said.
After meeting with multiple doctors, they discovered that there was a foreign object lodged in his left lung.
Manley has not decided whether he will contact Wendy's about the incident.
Wendy's spokesman Denny Lynch told The Associated Press that he has never heard of a situation like this in his 29 years with the company and said that Wendy's would contact Manley at the appropriate time.
"I'm just glad to get it out of me and get back to a normal life," Manley said.
The Associated Press contributed to this report.