Adult books similar to Winnie the Pooh

I loved Winnie the Pooh as a child all the way up to my teens, but I’m 21 now and looking for something more mature but that has the same sort of vibes. I love the childish and whimsical nature of Pooh, as well as the lack of action or stress, it’s just a very calm read. I have an anxiety disorder and I love anything calming. I’d love a nice chunky book, but I’m also cool with short stories or a collection of poems, etc.