In a 12 in x 8 in plastic container, I carry a small toolkit, pretty much everything in the cherokee comes apart with a 7/16 socket or phillips screwdriver. Paper towels, wire cutters & wire, quart of oil, the tow adapter if I don’t want/can’t use the tow bar. Blanket for laying on the ground (if needed). All the lamps are now LED so no extra bulbs. No fuses, everything is on breakers.
Anything else depends on type of flying. If a run for breakfast, not much else. Cross-countries depend on season of the year and which direction. I have a backpack that contains PLB, first aid kit, parachute cord, two carabiners, large garbage bags, a knife that will get me arrested pretty much everywhere else, handheld radio, flashlight & strobe with extra batteries, couple bottles of water, fire starter, candles, hot chocolate and lipton soup packets, 5 mil plastic, spare gloves, hat, underwear and a toothbrush. In a separate bag is the tie-down kit. In 20 years I’ve never used anything other than the tie-down kit. But then I was trained by CAP and emergency professionals how to deal with landing someplace I don’t want to be.
You’d be surprised what you can put up with when you have clean underwear. I learned that the hard way after spending 2 days on the wrong side of Eisenhower Tunnel when I-70 was closed and I slept on the floor of the hotel with a couple hundred of my newest friends. Ski pants are not comfy for sleeping.
I always carry either a 4 or 8 gal (summer only) tank of water for ballast in the baggage area.