Pythagorean said:
Well, at least this one is:
http://www.myfoxphoenix.com/dpps/news/offbeat/pea-of-life-grows-in-ny-man's-lung-dpgonc-km-20100810_9112207
This is by no means an appetising story, nor is it an everyday event, but it certainly is not without precedent. Seeds have been known to germinate in living human and animal bodies under various circumstances. I remember one particularly nasty case locally when a seed of a particularly nasty grass, known locally as "steekgras", meaning sticking or piercing grass germinated in the kidney of a little girl. The seeds are long, narrow, pointed, barbed and rigid. Usually they cause little harm except to the clothing and economy of the farmer on his land the grass grows, but they are barbed and if they stick into the flesh, they can work their way in. I assume that what happened to this girl was that in a romp she got stuck by a seed which she could not remove and forgot about. It wound up in her kidney before germinating. It must have been painful enough (kidney damage is fiendishly painful) to cause her to end up in hospital, where the surgeons discovered (and solved) the problem.
One seldom finds seeds germinating in lungs, because the coughing reflex in the trachea is extremely strong; get any irritating object, such as a food item, down your windpipe and you may well cough till your heart stops, but you will cough. (Incidentally, in case anyone reading this has never worked with a concentrated source of sulphur dioxide, believe me, it has much the same effect! As soon as it touches your windpipe you cough. You then instantly inhale in reaction, which means you cough again. This is a typical positive-feedback cycle and goes to competition in about one second, by which time your lungs are about as empty as you can cough them, and you are running like crazy to the nearest source of fresh air! Physiologically the gas is not particularly poisonous, but it has a peremptory way with self-confident laboratory novices.)
Seeds however. If one gets past the trachea, into the bronchi, one is past the point where the lungs stimulate the coughing reflex. This makes a certain amount of sense, because the ebb and flow of gas deep in the lungs is negligible, far too weak to eject a massive object like a seed. As a rule, if you cannot get rid of the object by bouncing upside down (as Brunel did when he swallowed a coin) then surgical intervention of some sort is about the only thing that will work.