I want to throw out my gf's storage jars.
That's odd. Why do you want to get rid of your gf's storage jars?
She keeps trinkets from her ex boyfriend in them.
Throwing her things away would be wrong. It will make her angry with you. You should try telling her that it upsets you that she hangs on to those things.
I don't care. I'm going to throw them anyway.
I can understand that you might be upset that your gf thinks of her old bf sometimes, but her knick-knacks belong to her and you tossing them is not your call. Stay away from her things and just let her know how you feel instead.