All of these photos are in the Memories section of the FamilySearch.org website and are tagged to Margaret Godfrey Jarvis Overson KWZZ-YBN. You can find all of the unknown photos by searching for "St. Johns" in the Find link. You should include the quotation marks in your search. You will find all the photos tagged to St. Johns in this way, including the unknown ones taken by the Jarvis and Overson families.
Here are some of the real treasures of the unknown photos.