If you mean you want to leave a binder with your receipts in, in the car, then don't. Don't leave any documentation in the car in case it gets stolen.
Really good things to have are:
- Some rope or thick twine
- A couple of bungees
- Duct tape
- Torch
- Wire
- Small tool kit containing at least: adjustable wrench, combi-screwdriver, knife of some sort, pliers
- Latex gloves
- Pen
- Paper
- Spare bulbs
- spare fuses
- Foot pump (or electric equivalent)
Don't forget your brain. It might help to go on an introductory car maintenance/troubleshooting course. It's very easy to panic and give up when your car refuses to start, but usually it's down to one of a few elementary problems. If you sit back and think it through, very often you can trace the fault and fix it yourself.