Well, didn't get as many as I'd wanted, but here are a few more...
1. A school bus
2. School supplies
3. New clothing
4. A crosswalk
5. Football (the ball or a game)
6. Change in the season
7. Homework
8. Summer's end
9. Playground
10. A Musical Instrument
11. A lunch box
12. Leaves changing colors
13. Exercise
14. A scoreboard
15. Harvest
16. Something brown
17. A barn
18. Something that you associate with September
19. Something cozy
20. A breakfast food