I never heard of grass being able to grow in lungs before.
But I'm a mold remediation contractor and have learned that mold can
grow in your lungs and your sinus cavities.
Source
INFECTIOUS MOLDS
According to a Mayo clinic study,
sinusitis caused by growth of fungus fibers or balls of fungus fibers in the sinus cavities is not unusual. This
is typically caused by common Aspergillus, Fusarium, and Curvularia species. Aspergillosis caused by the growth of aspergillus species in the lungs
most commonly A.fumigatus, A. flavus, A. Niger and A. territus species typically occurs in persons with compromised immune systems or a history
of lung disease that resulted in past lung damage.
Nearly any fungi can cause infections in persons with severely compromised immune systems.
What Aspergillus does when it grows in human sinus cavities and lungs (Aspergillosis) is that it fills the empty spaces, it is dark and damp in these
places, just what mold likes.
Aspergillosis - Centers for Disease Control
Aspergillosis - Wikipedia
A fungus ball in the lungs may cause no symptoms and may be discovered only with a chest x-ray. Or it may cause repeated coughing up of blood
and—rarely—severe, even fatal, bleeding. A rapidly invasive Aspergillus infection in the lungs often causes cough, fever, chest pain, and
difficulty breathing.
[edit on 27/9/07 by Keyhole]