Every teacher has his/her own reward system: treasure boxes, stickers, cheers, pencils, candy (gasp!), etc.
The system that has worked the best for me has been those little carnival tickets that you can buy at Wal-Mart, office supply stores, etc. When I catch them doing something great, I hand them a ticket. When they have a spare second, they put their name on the ticket, and drop it in the basket on my desk. Every afternoon I draw 3 or 4 tickets and those students choose from the treasure box, and on Friday I usually draw a few extra. What I love about this system is that you buy one roll of tickets, and it lasts more than one school year (and that's with being VERY generous with tickets throughout the school year!). Speaking of being generous, it's great to use these especially at the beginning of the year when you try to frontload the positive reinforcements of desired behavior! Doesn't cost an arm and a leg :)
I also like it because it gives me an easy way to affirm EVERYONE'S positive behavior, instead of accidentally rewarding the typical "good students" the majority of the time. The most difficult student in your classroom can do one tiny good thing, and it's an easy way to reward that one thing, not matter how trivial or monumental it was. It boosts their positive energy, and it gives them a chance to get something special later...gives them hope. If they DO get their name drawn for a prize, I try to say something to them like, "WOW! That great choice/hard work/whatever paid off! Keep that up!"
And of course, the more tickets they earn, the better chance they have at getting their name drawn! (I definitely use this example when it comes time to teach probability later ;)
As for storage of the ticket roll, I used to just keep them in my desk, but it was annoying not having the easy access to them. Well last year it occurred to me that we have a free-standing toilet paper roll holder from when we lived in a tiny apartment that didn't have one built in. So I went to our garage, and found it, and it was the PERFECT little dispenser for my tickets! I could leave them out and when I want to reward behavior I can just quickly tear off what I need and go! I can even tell a student, "Great job! Go grab a ticket!" I love it!
One thing I want to change this year is to have the students spin the "wheel of rewards" instead of getting a treasure from the box. This was Pinterest inspired...I saw a pin that used a lazy Susan attached to a wall as a "wheel of fortune" type wheel (genius!). HERE is the link to the tutorial. I am hoping to make one for the classroom that has 4 or 5 reward ideas (lunch with the teacher, work on the carpet, etc.) that they can spin for if I draw their name. I will post later when I complete the project and show you how it turned out!