This is a good start...
The Constituents of Medicinal Plants: An Introduction to the Chemistry and Therapeutics of Herbal Medicines https://www.amazon.co.uk/dp/0851998070/ref=cm_sw_r_cp_api_NeJ9BbXCG5JYA

Okay so this isn't complete, and apparently my account is too young (or doesn't have enough karma?) to make a post to the subreddit :(

But here is the original post I constructed to submit:

Hello r/herbalism.

This book list was compiled by a good friend of mine who has been a practicing herbalist for a while now. I thought you might all enjoy this list; it's divided into different sections based on the particular area of study. My friend would also like me to inform you "If anyone should have difficulty locating these books, I've found a website, called bookfinder.com, to be most useful in acquiring these books for a fraction of the price from regular booksellers."

Beginner Herbalism, General

• Rosemary Gladstar's Medicinal Herbs: A Beginner's Guide: 33 Healing Herbs to Know, Grow, and Use
  
  
• Making Plant Medicine by Richo Cech
  
  
• Modern Herbal Dispensatory: A Medicine Making Guide
  
  
• Rosemary Gladstar's Herbal Recipes for Vibrant Health
  
  
• Herbal Antibiotics: Natural Alternatives for Treating Drug Resistant Bacteria by Stephen Buhner
  
  
• The Herbal Medicine-Maker's Handbook: A Home Manual by James Green
  
  
• Earthwise Herbal Vol I. and Earthwise Herbal Vol. II by Matthew Wood.
  
  
• The Practice of Traditional Western Herbalism: Basic Doctrine, Energetics, and Classification by Matthew Wood
  
  
  
• Rodale's 21st Century Herbal by Michael Balick
  
  
• The Desktop Guide to Herbal Medicine: The Ultimate Multidisciplinary Reference to the Amazing Realm of Healing Plants in a Quick-Study, One-Stop Guide by Brigitte Mars
  
  
  
• The Herbalist's Way: The Art and Practice of Healing with Plant Medicines by Nancy Phillips, Michael Phillips, and Rosemary Gladstar
  
  
  

  Advanced Herbalism
  

  
  

• Medical Herbalism: The Science Principles and Practices Of Herbal Medicine by David Hoffman
  
  
• Adaptogens: Herbs for Strength, Stamina, and Stress Relief by David Winston
  
  
• Edward E Shook's Elementary Treatise in Herbology and Advanced Treatise in Herbology - (In regards to the second, my friend has found a free PDF of the advanced treatise.)
  
  
• The School of Natural Healing: The Reference Volume on Natural Herbs for the Teacher, Student or Herbal Practitioner by John R. Christopher
  
  
• The Complete Herbal Tutor: A Structured Course to Achieve Professional Expertise by Anne McIntyre
  
  

  Pharmacognosy and Phytochemistry (Part of the Advanced Herbalism List)
  

  
  
  

• The Constituents of Medicinal Plants: An Introduction to the Chemistry and Therapeutics of Herbal Medicine by A. Pengally
  
  
• Phytochemistry and Pharmacy for Practitioners of Botanical Medicine by Eric Yarnell
  
  
• Herbal Constituents: Foundations of Phytochemistry by Lisa Ganora
  
  
  

  Medicinal Mycology
  

  
  

• The Fungal Pharmacy: The Complete Guide to Medicinal Mushrooms and Lichens of North America by Robert Rogers
  
  
• Growing Gourmet and Medicinal Mushrooms by Paul Stamets