What should you read to become a profound, naturalistic, behavior-oriented thinker? I'm glad you asked. Here are some texts that hold up to close, extended study and critique. And, yes, I'm going to get obscure.
E. B. Holt, The Freudian Wish and Its Place in Ethics (1915) and Animal Drive and the Learning Process (1931)
John Dewey, Essays in Experimental Logic (1916), Experience and Nature (1925, revised 1929), Logic: The Theory of Inquiry (1938)
George Herbert Mead, Mind, Self, and Society (1934) and Philosophy of the Act (1938)
B. F. Skinner, Science and Human Behavior (1953) and Contingencies of Reinforcement (1969)
Morse Peckham, Explanation and Power: The Control of Human Behavior (1979)
Central works for understanding the nature of human behavior: Why do we act? What is the relation between "mind" (perception, emotion, cognition) and behavior?
Grace Andrus de Laguna, Speech: Its Function and Development (1927)
Alan H. Gardiner, The Theory of Speech and Language (1932, revised 1951)
B. F. Skinner, Verbal Behavior (1957)
John L. Austin, How to Do Things with Words (1962)
The books by de Laguna and Gardiner remain the two best books I've read on language. They have different strengths and so are in some ways complementary. De Laguna focuses more on evolutionary context and on speech within the broader ecology of behavior. Gardiner focuses more on the relation between language and speech—between conventions and acts. The books by Skinner and Austin are more flawed (IMHO) yet more widely known, and it is useful to understand how the ideas of de Laguna and Gardiner relate to the more popular concepts of verbal operants and speech acts.
John Dewey and James H. Tufts, Ethics (revised edition, 1932)
Edgar A. Singer Jr., In Search of a Way of Life (1947)
Elijah Jordan, The Good Life (1948)
Ian Morris, Foragers, Farmers, and Fossil Fuels: How Human Values Evolve (2015)
Edward L. Rubin, Soul, Self, and Society: The New Morality and the Modern State (2015)
The Dewey/Tufts book contains a lot of background on the history of ethical thought that can be got elsewhere, but it's useful to get a pragmatist/instrumentalist take on this. But Dewey/Tuft's Ethics also contains a more extended version of Dewey's holistic ethics which is summarized in briefer form in texts such as "Three Factors in Morals." Singer's and Jordan's books are underappreciated classics. Singer's book is slim but lucidly lays out a modern morality. Jordan's book is forbidding in scope but is based on a cogent philosophy of action and an almost painfully careful analysis of motivation and institutions.
Morris and Rubin extend the historical and cultural contextualization of ethics found in Dewey/Tufts. Both are extremely useful for understanding how morality emerges from deeper economic-political conditions.
Bertrand Russell, The Analysis of Mind (1921)
Edgar A. Singer Jr., Mind as Behavior and Studies in Empirical Idealism (1924)
John Dewey, Experience and Nature (1925, revised 1929)
Knight Dunlap, Elements of Psychology (1936)
Edmund Jacobson, Biology of Emotions (1967)
F. J. McGuigan, Cognitive Psychophysiology (1978)
D. O. Hebb and D. C. Donderi, Textbook of Psychology (4th edition, 1987)
Several of the books in other sections also discuss the problem of mind (Dewey, Mead, de Laguna, Skinner, Peckham, to mention a few), but this selection will drive home the naturalistic, physicalist interpretation of mind/experience. A few shorter works worth reading are Dewey's "States of Mind," Singer's "On the Conscious Mind," and Skinner's "Behaviorism at Fifty."
John Dewey, Art as Experience (1934)
Iredell Jenkins, Art and the Human Enterprise (1958)
Morse Peckham, Man's Rage for Chaos: Biology, Behavior, and the Arts (1965)