I have $300+ and Im 13? How do I spend it?

Honestly, I don't know if a hammock is something you would always use or even want afterwards. I would say that you could get a microscope, but then again you're using all of your money and you aren't doing anything major, I'm uming. I think you should rethink your options, besides you don't have to spend it now. You could upgrade your computer or even buy a netbook if you want to.