More and more there are children's books that are aimed at trans and gender nonconforming kids. Below are some of my personal feelings about the ones that I have read. Note that these are the opinions of one person and you may find that you have other feelings about these books, so I encourage you to check them out at your library or your local independent bookstore.
Are You a Boy or a Girl? By Sarah Savage, Fox Fisher (Illustrator)
A very simple book about a non-binary kid who moves to a new school and keeps getting asked "are you a boy or a girl?". It talks about how activities and professions are not just for boys or just for girls and has a nice resolution at the end "I am me". I'd recommend it for kids 7 and under.
I am Jazz, by Jessica Herthel and Jazz Jennings, illustrated by Shelagh McNicholas. (New York: Penguin).
This is the book that we read to our kid and she exclaimed THAT IS ME!, so I have a lot affection for it. It teaches about being transgender, but also uses the "wrong body" narrative which I'm not totally into. It also equates liking pink & stuff with being a girl, which again, I am not super into. BUT it is the book we gave to our kid's teachers, class, cousins to help them understand her. It is a very accessible book for anyone who needs help understanding what it can mean to be trans, and the illustrations are adorable.
My Princess Boy, by Cheryl Kilodavis, illustrated by Suzanne DeSimone. (Simon and Schuster [KIDS.SimonandSchuster.com]).
Boy oh boy, do I NOT like this book. It's a story about a parent's work to understand her boy kid wearing dresses, and the importance of compassion and/unconditional love. It was one of the first I bought for my trans kid when she started wearing dresses, and personally I feel like it was a big mistake. None of the people have faces, and the story has a tone that seems better suited to parents who are struggling with accepting their kids rather than meant to empower kids. It puts a kid in the position to need to protect her or his parent's feelings. At one point it even says "And when he buys girl things, they laugh at him, and then they laugh at me. It hurts us both." I believe in being honest with your kid about your feelings.. to a point. I'd worry that this sentence puts the burden on the kid to protect the parent's feelings and that is NOT the job of little kids.
Jacob's New Dress, by Sarah and Ian Hoffman, illustrated by Chris Case. (Albert Whitman and Co.)
This book is great if your boy kid likes to wear dresses but does not ID as a girl. It is a positive book about how boys can wear dresses and everyone else can shut it. It is upbeat, positive and the illustrations are pretty good too.
Backwards Day, by S. Bear Bergman, illustrated by KD Diamond. (Flamingo Rampant).
One of the first books we found that talked about gender; I like this book. Set on the planet Tenalp where everything is backwards from the way it is on our planet, except for one day a year when everyone and everything is backwards. It is longer than it needs to be, but the story is cute and all the people are vibrant colors so it is not so very "white" like many of the books we have found. It is about a girl who longs to be a boy—and gets to!—so it is a rare book in this category, and it walks through the parents being confused and counseled by experts to accept their kid.
Meet Polkadot, by Talcott Broadhead (with an introduction by Dean Spade). (Olympia WA: danger dot [dangerdot.com]).
Lost of BIG words and concepts. This not much of a story but it covers lots of ideas about gender that are great. Even though I'd recommend it for maybe 8+ years olds, my 5-year-old requests it. This geared more towards folks who might ID as gender-neutral, fluid or queer and the illustrations are right up my alley.
A Princess of Great Daring, by Tobey Hill-Meyer, illus. by Elenore Toczynski. (Flamingo Rampant).
This is a story about Jamie, who is about 11, and hasn't seen her friends all summer. Now, she's getting together to play with them and tell them that she identifies as a girl—not a princess needing to be rescued, but a princess who can be a hero too! The friends play together, with the boys all being boyish in different ways and accepting Jamie for who she is. They all have a great time, and Jamie knows that when she starts school, her friends will have her back. This is one of our favorite books to read our kid because it is fun, positive and really easy to understand.
A Girl Like Any Other, by Sophie Labelle. (Montreal: SGLeditions).
I like this book a lot, as does my kid. It is a little silly, and so right-on. It is a first-person narrative of a young trans girl, who points out on page one that all girls are different from each other and all boys are different from each other. Instead of the "wrong-body" narrative, it frames gender as located in the mind and not the genitals. I do admit I hesitated to read it to my kid because it talks about being left out because of her gender, but that is the truth of the world and something that we should talk about.
Be Who You Are, by Jennifer Carr
Sadly it looks like this book may be out of print, but I quite like it. It's another version of the getting-to-be-typical story of a trans girl struggling to be her authentic self, and it does have my unloved "wrong-body" narrative, and they use "he" a little longer than I think they should. BUT the parents in this never seem reluctant at all to support their trans kid and for that I love this book. If you can find it, snap it up!
Yeah, you may have noted that there really aren't a lot of books aimed at trans boys... I haven't really found many of those... Have you? If so, let me know!