Does any boy know what causes a yellow tongue?

My tongue turned yellow, it’s not swollen, it doesn’t hurt, my skin is not yellow, my eyes are not yellow, I don’t have bad breath, I feel great. but my tongue is yellow. It looks like I would of eaten a yellow candy, but I haven’t. Anybody know what may be causing it?

That is usually caused by liver problems.
You should probably see a physician as soon as possible.

What can I eat that can remove the plaque at the back of my tongue?

I have removed most of the plaque on my tongue however I do close my mouth for a minimum 10 minutes and all the plaque then returns. I can never get to remove the plaque at the back of my tongue which is causing the bad breath. So what foods can I eat that will move that plaque away?

You simply need to brush the back of your tongue as well as the front. The back is more sensitive to the gag reflex but it is still necessary to brush it. Try a tongue scraper, sometimes this can help reduce the gag response. Eating food would not disrupt the plaque enough to remove it.