I do enjoy when I spot letters around that weren’t necessarily intended to be letters. (Punctuation marks, too.) Here are a number of exes I’ve spotted in the wild in recent years.
Hydrant.
Barn doors.
Fallen trees.
Library building.
Tree roots.
Tree branches making an X and a Y.
collecting tokens 
These are fantastic! This seems like a great exercise for a photo challenge!
I especially like that last one, which gives me a mathy sort of vibe with the X and Y.