The following is a terrific plan from the University of Tennessee Extension. The school has compiled a list of the plans that are primarily for agricultural applications. There are more than 300 free plans provided (Free Plan List).
I selected a nice plan that can be used throughout the nation and would be easy to modify to suit most environments. If you have a camp site and need a simple open air shelter or are looking for something on a walking path, or a golf course to protect visitors from weather, this plan (or others at the site) is a great option.
The site even includes plans for cottages, out buildings, boat houses and more. A great free resource.