Most valuable possession?

We've been talking a lot about being thankful. I've really been thinking each day what I am thankful for. It's made me realize some of the things I put a high value on, and possessions that I don't even really care about (and should get rid of!)

So- let's say that your house was on fire, or a flood was coming and you had to grab a few prized possessions- what would they be and why? (and this is assuming that all of your family members and pets are already out safe so you can't pick them:) What material possessions do you value? Why?