RE: Things you've found...
I never really went out seeking abandoned houses, I just wandered across them.
I was out fishing with my friend and we came across an island which a river looped around, on the island was an abandoned farm house. Inside the house was so much cool stuff, like a really old TV, and some old toys. The barn had an old Model T, an old tractor, several engines, and random stuff like that. Everything was no newer than like 1960. We grabbed a few small things, but left the majority of it alone. It was pretty eerie, and looked like these people just up and left. There was still canned food in the cupboards, and a half bottle of whisky under the sink. A car was sunken under the remnants of the dock we tied up to. This was back in Washington, when I was about 16, I have no idea if the house is still there.
A friend and I found another one that had a VW bug in the garage, in really good condition. We were pretty young back then, and scared to touch anything.