Over the years, I've really settled my EDC into a small, but useful kit.

The three things I ALWAYS carry are:

Multi Tool
Bandanna
Key Ring with Flashlight (Pico), Whistle (Fox) and Tiny Pen Knife (Swiss Army). Ok, that's technically three items right there, but it's ONE keyring, so I count it as one item.

Also, I'm going to be repacking my 100% non-hypothetical kit again, a kit that I developed as a fire/rescue guy and it was/is a kit that had a lot of stuff in it that I actually used in actual emergencies. There's a few surprises in there.