Ron Sveden had been battling emphysema for months when his condition deteriorated.
He was steeling himself for a cancer diagnosis when X-rays revealed the growth in his lung.
Doctors believe that Mr Sveden ate the pea at some point, but it "went down the wrong way" and sprouted.
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Mr Sveden said the plant was about half an inch (1.25cm) in size.
"Whether this would have gone full-term and I'd be working for the Jolly Green Giant, I don't know. I think the thing that finally dawned on me is that it wasn't the cancer," Mr Sveden said.
He is currently recovering at home with his wife Nancy, who joked that God must have a sense of humour.
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