All the time - an analogue wristwatch and a pocket knife, cash and a mobile phone.
For trips out, depending on destination/geography/distance -
On me - Gerber multi-tool, Opinel folder, fixed blade full tang camp knife, flint striker, lighter.
In truck - Spare fuel/oil/trans fluid and brake fluid, fork/spoon/plate/mug, 25L water, tools, rescue equipment (Tracks, snatch strap/bow shackles, airbag jack, compressor, long handled shovel, rope), repair stuff (Silicone self amalgamating tape, insulating tape, duct tape, spare belts/hoses, nuts/bolts/washers, headlight/brake/indicator bulbs, fuses, reel of 30 amp auto wire, crimp terminals). Self inflating camp mat, hammock, tarp, sleeping bag, blanket, headtorch, spare LED torches, gas hot plate with spare cylinders, cook set, 2 x fire extinguishers.
Spare Shades/boots/socks and a wooly hat!
Umm, sometimes more...