Tonight I finally learned why he does this.
Daddy said, "Isaak calls their insides 'sleepy seeds'. He doesn't like to eat them because they are like the sleepy seeds in his eyes."
I never knew this. Makes perfect sense now. Do I push him to eat what he thinks is gross or not? He's a really good eater otherwise. In fact I think he eats the seeds once they are out. He just doesn't like to eat them when they are in tack. It just takes a long time for him to eat the "sleepy seeds"!