It's a good idea for all Amateurs to have some gear in one place, because you never know when a disaster might strike -- even if it's not a callout.
Here are some *suggestions*. Perhaps it will get you started on making your own list so you can pack your bag. Keep your list handy so you can grab your last-minute items normally kept elsewhere or actively used.
PERSONAL ITEMS: Uniform, ID cards, FCC and DMV licenses. Safety equipment: flashlight, goggles, dust mask, gloves, hearing protection, rain gear, chem-lights. Personal items (for 24-hour duration): food and utensils, water, first aid supples, waterproof matches or cigarette lighter, extra prescription glasses, personal medicines, personal hygiene items, extra clothing, sleeping bag or "space blanket, change for telephone call.
ADMINISTRATIVE: Notepad, writing implements, maps, log sheets, phone lists, clock, frequency lists, repeater directory. You might also like to tip out the white pages of the phone book, or at least the front section, which gives all sorts of useful information.
COMMUNICATIONS: Transceiver, portable transceiver, headphones, microphone, power supply/batteries/battery pack, adapters, antennas, cigarette lighter adapter, patch cords, barrel connectors, elbows, pocket knife, fuses, alligator clips, solder and iron, SWR bridge, VOM,
TOOL KIT: Screwdriver, pliers, dikes, black tape, extension cord with multiple outlet, adapters, light nylon cord.