Ok in this movie a bunch of kids set out to find a treasure. They float down a river and the fat kid has Twinkies. There's a woman who seems creepy (evil witch)? And a boy who's a trouble maker. It is not a cartoon, going crazy please help!

Maybe one of the movies here is what you're looking for.

Treasure Hunts movies (http://www.allmovie.com/characteristic/theme/treasure-hunts-d523)

Maybe this?
The Lil' River Rats and the Adventure of the Lost Treasure Movie Details in Denver - Denver Post (http://calendar.denverpost.com/movies/show/16697-the-lil-river-rats-and-the-adventure-of-the-lost-treasure)