I don't know whether I'm the boxer or the bag
While the meaning could be as above, as Eddie Vedder usually changes the lyrics of the song any time he sings it, he sometimes sings this part differently:
“I don’t know where am I: on the box or in the bag?”
Since the overall meaning is a soldier’s death, Eddie does not know if the dead body is in a box (coffin) or in a body bag.
To help improve the meaning of these lyrics, visit “Yellow Ledbetter” by Pearl Jam Lyrics and leave a comment on the lyrics box