There is a place in Janesville, Wisconsin called McFarlanes. I think that they are the worlds largest hatchery for Pheasant. I also believe that they may have pidgeons (or at least a line on where to find them). Here is the internet website.

http://www.pheasant.com/

You may also want to call up the local Pheasant Forever chapter and find out if any of their members raise/sell pidgeons for training. Game farms/hunt clubs would be another avenue.

Pidgeons don't need to be covered in scent to help your dog. Once it gets the idea about what it is scenting you'll be fine. Pidgeons are used for training because they are incredibly hardy, cheap and (as Mite said) have a really strong smell for a bird.

Good luck.