Off the top of my head, I think of three cookbooks that are treasured by me and my family but who I would think many people may have never heard of.
1. The I Love to Cook Book by Lauren Groveman was my unconventional first cookbook because it was the one I learned to make really really good muffins from as a teenager--still my muffin recipe of choice. She has (had?) a PBS show which is how my Dad found the book I believe. Lauren is a great teacher, and the book has a great balance between modern and traditional, simple and challenging, and homey and impressive. I highly recommend it, especially for a new cook who wants to learn to make everything from AMAZING muffins and scones to corn pudding, AMAZING braised leeks, grilled meats, seafood, fresh pasta, and a nice variety of home baked bread items! Lots of pretty pictures too.
2. Greyston Bakery Cookbook by Sara Kate Gillingham-Ryan is a fantastic little baking book. It's an unassuming looking book in a world of Dorie Greenspan and Baking Illustrated cookbooks, but there is one interesting recipe after another, and they're ALL very do-able. I tend to go to this book when I want to make something that will make me look like a brilliantly creative pastry chef without trying too hard. There is something called an Olive Oil Sherry Souffle cake that I've been meaning to make for so long, and an Earl Grey Tea Cake which, hello, yum.
3. Recipes from Home by David Page and Barbara Shinn from the cozy NYC restaurant of the same name is like looking into someone's treasured family album interspersed with heirloom recipes. The only reason you NEED to get a (now super cheap) copy is the mac and cheese recipe with roasted tomatoes. With only a few tweaks it's become my family's own ultimate mac and cheese. I'd trust their version of almost any classic midwestern dish, of which many are represented in the book.
Oh yeah, one more! Beth's Basic Bread Book by Beth Hensperger (same author as "The Bread Bible") has the most perfect yeasted cornmeal honey bread that's it's hard to believe it comes from a beginner bread baking book. Truly, it's my favorite bread. The book has many recipes with step by step illustrations and detailed instructions. It's only 156 pages, which for a new bread baker is probably less intimidating, but Ohhh that bread...
Hmm, that's all I got right now. Wow these all have really horrible names, don't they? Don't judge a book by its name, please!