Though not that original, I want to recommend Timoshenko. Since many people have mentioned it already, I will discuss a Brief on Tensor Analysis by James Simmonds. Though not always useful, I sometimes use it to remember tensor rules that I have forgotten. The book is divided into chapters as follows:

I: Vectors and Tensors

II: General Bases and Tensor Notation

III: Newton's Law and Tensor Calculus

IV: Gradient, Del Operator, Covariant Differentiation, Divergence Theorem

Again, sometime it is not that useful and you spend your time trying to read it while not learning much, but it does come in handy sometimes. You can see the amazon link:

Amazon

I would like to recommend "Elasticity: Theory, Applications, and Numerics" by Prof. Martin H. Sadd as a reference for ES240. The book, as its name indicated, is mainly focused on elasticity theory and its applications, but also discusses numerical methods such as finite element method and boundary element method.

Prof. Martin H. Sadd, organized the book into two parts: I. foundations, and II Advanced topics. In part I, the book clearly outlines the basic equations of elasticity, i.e. strain/displacement relation, Hooke's law, and equilibrium equation. The other context of part I is devoted to the formulation and solution of two-dimensional problems. This structure matches the progress of our class very well.

The second part of the book begins with the discussion of anisotropic elasticity, thermo-elasticity, and micromechanics. These topics are complementary to the notes of ES240, and helpful in solving homework problems. In its last chapter, the book introduced finite element method and boundary element method.

Book Title: Mechanical Behavior of Materials: Engineering Methods for Deformation, Fracture, and Fatigue (Second Edition, Third Edition released earlier this year)

Author: Norman E. Dowling

Amazon.com Review Link

The book starts with a general overview and introduction to the mechanics of materials, but later emphasizes deformation, fracture and fatigue of materials. The following is a list of the chapters in the second edition:

(1) Introduction- Discusses types of material failure, design and materials selection, technological challenges, and the economic importance of fracture.

“An Introduction to the Mechanics of Solids” by S. H. Crandall, N.C. Dahl, and T. J. Lardner

As the title explains, this book shows very basics of the solid mechanics. The book has a good coverage of the concepts of primary elements of mechanics, the three equations, some environmental effect, and examples of torsion, bending, and buckling. This book elaborately explains/proofs several important equations, whose procedures tend to be skipped in many courses due to time limitation. Various case studies/problems accompanied with suitable figures have always helped me to get better senses. It is also easy to find what I am looking for in the book with neatly sorted tables and index. And most importantly, I like this book since the book discusses engineering applications and the limitations of these models.

The materials given in ES240 exceed the range that this book can cover, but this book still is a good resource to go back to when I forget the basics since my sophomore year when I used as our textbook for the materials and structures.

So besides using Timoshenko (which is basically the bible of solid mechanics), I have been using Slaughter's The Linearized Theory of Elasticity which I came across in the Gordon McKay Library.

Unlike some of the other textbooks, there is a big focus put on the theory and the idea behind the examples while still having many worked out problems. The first few chapters give a big refresher course on mathematics and lay the groundwork for what is to be taught later on.

I came across this book in particular for the in depth coverage of Airy Stress Functions.

The book is broken into 11 chapters:

Review of Mechanics of Materials
Mathematical Preliminaries
Kinematics
Forces and Stress
Constitutive Equations
Linearized Elasticity Problems
2D Problems
Torsion of Noncircular Cylinders
3D Problems
Variational Methods
Complex Variable Methods

If you prefer to learn tensors in solid mechanics, Nye's book is recommended.
The author covers most of the physical properties in various crystal structures. Some handy tables are included in the book. However, he uses ONLY tensors to derive the properties. If you prefer to write down equations one by one, this would not be a suitable book to start.
Timoshenko's book is also recommended too. As a beginner, this book explains not only the problem, also the meaning behind it. It clearly describes the fundamental questions.
Some books

Although I know it is not very original, I am recommending Timoshenko's Theory of Elasticity textbook. I find this book useful because it solves many classical solid mechanics problems without assuming the reader has a strong background in the subject (like me). When I am having difficulty with a homework problem, I turn to the index and it usually directs me to a section of the book directly related to the problem, or sometimes even the solution itself. Many parts of the book complement the course, such as the chapters "Plane Stress and Plane Strain" and "Analysis of Stress and Strain in 3 Dimensions."

The book starts with basic definitions and derivations of stress and strain, then applies these equations to solve problems in different coordinate systems. It also includes chapters on more specific topics, like torsion and thermal stress.

It's a bit hard to recommend a text, when I have yet to find one that I really love. Currently I am working from Advanced Strength and Applied Elasticity by A.C. Ugural & S.K. Fenster. It contains all of the relevant information, though I find the explanations of the concepts a bit slim. So far is has covered all of topics we covered in class. The first four chapters seem the most relevent. These are titled Analysis of Stress; Strain and Stress-Strain Relations; Two-Dimensional Problems in Elasticity; and Failure Criteria. The rest of the text deals with more specific topics (torsion, bending, plastic behavior, etc.).

Here is a link to the Amazon page, where the book gets mediocore reviews.