I discovered a useful book that I am bookmarking here, called The Valdris Book: A Manual of the Valdris Samband. Written in 1920, it appears to be a history/reference book dealing with “the history and description of the Valdris samband, an organization composed of people from the geographical area known as Valdres in Oppland County, Norway who immigrated to the United States.” A quick search of the book’s index shows that my great-grandfather, Mons Fuglie, is mentioned in this book along with his wife, Louise Haldorson. Both were still alive when the book was written.
This book looks like it will be very useful and interesting, and it appears to be widely available including a free ePub format provided by Google Books.