Unfortunately many town no longer have a dump. the last place I did that had one put up a sign telling up dump hyenas that we were not welcome, but, like elliot says, as long as you weren't too blatant about it, they pretty much looked the other way. I think it's a matter of liability (thanks again, you $#^$%&*$# lawyers).
The town I used to live in had a good old fashioned dump. That place was a gold mine!!!! I am fairly sure that I took more out of there than I left.
Another idea, if you are looking for scrap metal/wood/whatever is to put ads in your local town classified type paper telling folks you'll gladly come cart away such stuff. These ads are generally free.