The secret to finding treasure is to look in places that nobody else ever looks. I'll share with you guys one of my techniques that I once to used to great effect in my youth. Go to a junk yard and make friends with the owners (alot easier said than done) so they give you access to all the cars before they get squished.
Look in all the cars for treasure - under the seat cushions, center console, glove box, trunk, etc. Nearly every pair of luxury branded sunglasses I have ever owned, and I have many, have come from the overhead glasses compartment over the center console of junkyard cars. People always seem to have forgotten their sunglasses up there. You will also find tons of change throughout the cars.
It's perfectly reasonable to estimate the value of the spare change alone, let alone the rarer treasures, that gets crushed inside recycled cars each year equates to tens of millions of dollars. May as well salvage some of it! Keep the junkyard workers well supplied with treats and soda and they'll welcome your visits every day. I did this for over 10 years.