Shel Silverstein, 1964
For a book deemed "Kindergarten to Second Grade" level, this book has some pretty deep themes. A boy takes and takes, while his poor friend the tree just gives and gives and gives, until eventually it has nothing left to offer the world but a tired, soulless shell worth no more than its weight in future IKEA furniture. It's a heartbreaking commentary and if you were born in the 70s, you probably got this at your 8th birthday party from that aunt you never see.
It's noted that "Silverstein had difficulty finding a publisher for The Giving Tree." An editor at Simon & Schuster rejected the book's manuscript because he felt that it was "too sad" for children and "too simple" for adults." Well, good thing it eventually found a home because no other book of its era has so succinctly summarized exactly what parenting feels like.
This one is good for reading to your kids when you're feeling a bit passive aggressive and/or feeling like they stole your youth.
Tissue Factor: 3/5 tissues and one "I gave my life to you, you ingrates!" speech.