Scratch

I didn't come up with this age limit. Sorry if you're 14 or older.
Anyway, click here to see what I'm talking about. It's a magazine I found out about for kids [ages 8 to 13]. You can submit your a story that's 2,500 words or below (and, if you want to, illustration(s) to go with it). They get like hundreds of submissions a week though, so you might not get in, but if they really like what you've written they will publish it in the magazine and you'll be paid $40 for it!!! Also, per (full-page) illustration, $25 each. If they like the illustration but not the story, they will suggest you become a Stone Soup illustrator and illustrate for other people's stories. If they like the story and not the illustration, then they will publish the story and have an illustrator illustrate it.
Check out the website for more information