Your “comfort” book
Rootabaga Stories by Carl Sandberg.
I first read this book when I was fairly young. The stories ‘were born of Sandburg’s desire for “American fairy tales” to match American childhood. He felt that the European stories involving royalty and knights were inappropriate, and so set his stories in a fictionalized American Midwest called “the Rootabaga country” filled with farms, trains, and corn fairies.’ 
Alongside the traditional fairy tales brought over to North America from Europe, I grew up in Canada reading Rootabaga Stories, and they spoke to me much more strongly than the Brothers Grimm. There was a sense of adventure alongside a definite level of ridiculousness in the stories; they were crazy enough that you could believe they were true.
You get to the Rootabaga Country by train, and I’m sure it’s this book that created my childhood love of trains (that, and travelling by train from Vancouver to LA and across to Albuquerque and back again in an awesome trip that involved Disney Land and Universal Studios).
There’s something very reassuring about the idea that you can get to a mythical land if you just go far enough in a train, or on a bike, or by bus. The idea that escape is always an option, if life gets too bad.
That is why we read fiction, after all. To escape into another world, if only for a few hours. I’ve spent my life finding new ways to escape every situation — so is it any wonder the books that bring me comfort are the ones where that fantastic land is just around the corner, and I’ll see it if I just squint my eyes the right way?
Time and time again I pick up this book and read through it, and find myself content in the knowledge that if it is so far, so early, and so soon, that I can get a long slick yellow leather slab ticket with a blue spanch across it and I will ride where the railroad tracks run off into the sky and never come back.