As to finding a wallet. In the US, it's my understanding that you can drop it in any blue Postal box and the Post Office will deliver it to the address. If there's a lot of cash in it, it may be worth contacting the owner as he/she may offer a reward. Of course, you could pocket the cash and then drop it in the Postal box. I guess it depends on whether your conscience would bother you or not.
Once I bought a pair of identical used laptops on ebay. One had a bad motherboard but a good screen, the other was in working condition but had a bad screen. The guy was planning to make one working laptop from the two machines but never got around to it. I completed the project. I looked at the hard drive by connecting it to a USB to IDE cable. It had some files on it, documents etc. and almost a CD worth of photos. I burned this stuff to a CD before formatting the drive.
I contacted the seller to ask if he wanted me to send the CD to him, he said no.