Partridge berries (Mitchella repens) are small, round, deep red berries that grow on bushes very close to the ground. They are most prevalent on the barrens. Their tart flavour is prized for jams, muffins and loaves by those who appreciate it. (I find them to be an acquired taste as they can be rather bitter.)
You can use these berries in just about any baking that you would normally use blueberries in, but you should add a little sugar to the recipe to balance it since blueberries are sweeter. Some example: partridge berry muffins, partridge berry pancakes and even partridge berry coulis on pork tenderloin! (I had this at a restaurant, so unfortunately I have no recipe for it...dommage!)
Rodriguez's Markland Cottage Winery in Newfoundland uses this berry in it's berry wines, as well as strawberries, blueberries and bakeapples.
References:
http://www3.nf.sympatico.ca/rodrigues.winery/index.html
http://www.baccalieu.com/yaffles/partrid.htm