Mom won't let me bring pillow to cl, how to convince her?

I know it sounds like I'm a really bratty kid, but I don't do ANYTHING in English cl (kids bring their laptops, listen to music, it's basically a free period) The teacher doesn't do anything or try to control the cl. How can I convince my mom to let me bring a pillow? Also if you think I'm a bad student, I have an 87 average and my mark in English is 85.