My mother left me a cookbook that is the most amazing one I have ever seen. It is approx 1700 pages, the last pages are missing on my copy. I remember the cover, which is long gone, was green. It is definitely American as it has instructions for dressing American game. Also includes canning, preserving and pickling. As well as freezing, menus, diet patterns, a homemaker's handbook for purchasing fruits and vegetables. Also instructions on stretching the food dollar. So my question is how or where can I find out the name of this cookbook?
Choose some unique phrases from the book (things you don't expect to appear in many other books) and search for them (in quotes) in Google books. Look at the scanned pages in the search results and see if they match your book.
If that doesn't work, try a general google search, again with the phrase quoted. (If you're looking for an old cookbook and it's on the web, it's likely at Google Books or archive.org, but there are some other, smaller collections out there.)
If you get too many results, you can take a 2-3 of the chapter headings or phrases and do a search for the combination. You'll want to choose headings that you don't expect to both appear in many books. E.g.,
If an online search doesn't work, you could also try asking a librarian or bookseller who specializes in old cookbooks. They may know the book or have more resources to look it up.
This follows the advice given in Steve's answer, except for a description of the book instead of the contents.
Since there probably aren't that many 1700-page cookbooks, I went to Google and looked up:
"1700 page" cookbook
The second hit was for a forum post at "The FAL Files" describing a book that pretty much matched your description. The book is called:
Meta Given's Modern Encyclopedia of Cooking
Published by J.G.Ferguson, it has a green cover and comes in either a 2-volume set, or a complete all-in-one book. The complete version is 1699 pages. You can find it on Amazon.