Which one was your favorite? The one that I will entitle, "Cliff!"? Or the one that we, as a class, called "The Trap"?
Those stories come from an excellent website and resource called FanFiction. Find it here: http://www.fanfiction.net/.
For more alternative endings to The Giver, search for "The Giver" in the searchbar (top right). For a direct link, click here.