The Boy Who Didn't Believe in Spring is often an underrated, but very good book. It explores the reactions and beliefs of two boys, King Shabazz and Tony Polito about whether Spring exists. King in particular, doesn't want to believe until both boys see flowers growing out of the ground in a junkyard area.
The Boy Who Didn't Believe in Spring a very good children's book for the early 1970's, that doesn't get mentioned much for Spring books in elementary educational curriculum today, but may have been more relevant back then as a period piece book in 1973.