Is the yellow part of a walnut poisonous?

I ate the yellow part and then my stomache started to hurt. Is it poisonous?
Answer:
I grew up with lots of Walnut Trees and ate many over the years. They are a great food and good for you.
If the walnut had meat that was yellow then it did not ripe correctly on the tree. If it is black it is rotten. The meat should be brown on the outer surface and beige on the inside.
Do not eat walnuts if the shell is cracked as bacteria can enter the meat.
Walnuts are not poisonous but they can go bad usually if it has been on the ground sitting in water or wetness, if germs or bacteria get in a crack shell, if someone picked it off the tree, or if too old. Walnuts are only ready to eat when they shed their skin and fall to the ground.
We used to spend time picking them off the ground, bagging them in burlap sacks and selling to walnut buyers (companies). And we always kept plenty to eat by hand.

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You are probably allergic if not poisonous.

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There's a yellow part? hmmm.
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