Is it illegal for companies to put mercury in toys?

I took apart one of those "bobble clocks" that speaks, and there is a small mercury bead inside that completes a circuit which enables the clock to talk. I want to know whether or not this is legal in the U.S. I wonder because it was made in China and patented there, also. Please don't give just"yes" and "no" answers. If you find a law that shows this is illegal, I want the name, somewhere on the internet where I can verify it, etc.