Have jade medallion on one side there's a running horse on other a dragon with ball in it's mouth. Is this worth anything?

I think it may worth something.
The dragon and the horse pattern may stands for a Chinese four-character idiom called "Long Ma Jing Shen", which means full of energy. It has a propitious meaning. Besides the medallion is made of jade, so it may worth something.
But in order to make sure, it is suggested find a expert to look for you.