Reddit mentions of Nature Bound Pocket Field Guide

My suggestions are all of the "bug-in" variety, FWIW.

-- Two gardening books that any potential seed savers should have: "Seed to Seed" by Suzanne Ashworth and "How to Breed Your Own Vegetable Varieties" by Carol Deppe. Deppe's book sounds esoteric, but is actually a fantastic guide to using the scientific method on a small scale to maintain or or adapt seed varieties.

-- A free tl;dr pamphlet for seed saving can be found here. Good to print out and keep with a seed vault.

-- Another gardening guide -- especially useful for the spreadsheet lovers among us -- is "How to Grow More Vegetables," by John Jeavons. This one details the double-dug intensive bed method of gardening, which strives to maintain fertility without animal input. But the real beauty of the book is in the charts, which give caloric nutrients densities of food, potential yields (divided up into low, medium, high, depending on how improved the land is), plant spacing for maximum yields, etc. These numbers allow you to make back of the envelope calculations on, for instance, what square footage you need to produce X pounds of beans resulting in Y amount of calories, and how many Z lbs of seed beans you'll need to plant that area.

-- Both local and widely adapted foraging guides. I like Nature Bound for a quick and dirty portable guide, but there are tons out there. Good photos are essential if you are unfamiliar with identifying plants.

-- "The Art of Fermentation" by Sandor Katz. How to make beer, wine, bread, pickles, sauerkraut, yogurt, weird stinky meats, etc. without a lot of fussy equipment or special purified yeasts. Must-have book on preserving food without electricity.

-- USDA canning guide, also free. At a minimum, the introduction is worth printing and throwing on the shelf with the cookbooks.

-- "Encyclopedia of Country Living" is a good one-volume homesteading guide.

-- Humanure Handbook. Everything from composting toilets to safely using shit as fertilizer.

-- And finally, here's an amazing number of useful old public domain books that will keep you busy for weeks.