This will be my first year to teach 3rd grade. I have taught middle school and have nothing for this grade level. I would be so grateful if anyone would share a website that they use for file folder games.
I'm not sure if this is what you are looking for but Mailboxe has a book of best math games. They have different grade levels. The one that I got was specific for grades 4-6. It covers all topics and I used it for my 5th graders and they absolutely loved them! They always wanted to play the math games and never realized that they were learning as well. Other teachers in my building are constantly coming to my room for my math game book. As I introduce the games to the classroom I then make a file of it and the students can then play the game whenever they have free time.
It is designed for grades 5/6 but all the activities can be adapted for other grades. There are tons of ideas for file folder games (though they aren't labeled as such) and portable centers. I just browsed through the spelling activities and games and they are great. Lots of things you can copy to Word and print out.