Things I Googled while on hold with Pediatrician Man's weekend phone nurse:
Foreign Body in Nose
Gray Nasal Discharge
What Charlie says when you ask him what he put in his nose:
"I'm a monkey!" followed by maniacal laughter.
UPDATE: The nurse suggested I put my finger over the unaffected nostril and then blow into Charlie's mouth like I was giving him CPR. On the first try, the corner of whatever it was started to show. I tried again and it was obvious that whatever it was was BIG. It took FOUR TRIES to get the thing out. It finally popped out and Charlie was visibly more comfortable (once the screaming from "the procedure" had calmed down). Whatever it was was big (approximately conical, a quarter inch in diameter and a half inch long) and brown and hard. We think it was part of a banana stem (hence the monkey references from Mr. Helpful). I think he had it in his mouth and then a sneeze propelled it into his sinuses because there is no way it went in there through his nostril. Now I know why he was such a crab all day! Poor little guy.
Picture taken this morning shortly after presumed lodging of banana stem in nose and shortly before I said to Ryan "Should I be worried that he has black snot coming out of his nose?" Of course NOW it is quite obvious that something is in there.