Since many of the stories of the Elder Wood are retold older stories, with significant changes, it seemed only fair to tell you which ones are which. Spoilers, obviously, of a sort:
1. Into The Wood is a recursive story, which is usually a conceit for a one-paragraph story.
2. Little Nut is Snow White.
3. King Haifyd is The Emperor's New Clothes
4. Salt And Bread is the Pied Piper.
5. My Blood, The River is The Giant Who Had No Heart
6. Love And The Beast is Beauty And The Beast
7. The Hive In The Hill is Dedalus And Icarus
8. Most Generous is Rapunzel
9. Hugh The Boastful is Rumplestiltskin
10. The Four Hearts isn't a story.
11. Every Sheep Is Stolen is Prometheus
12. Saesin Proverbs isn't a story; also, most proverbs given are recast proverbs from various cultures.
13. Rionna And Red-Hood is Little Red Riding Hood
14. The Quarrel Of The Kings is a section of the Tain Bo Cuillagne, recontextualized.
15. The Words Of Milus isn't a story.
16. What Makes A Man is original.
17. Ardion And Baedwyn is Pygmalion and Bloduewedd, both.
18. I Will Teach Thee is a composite of many oaths and codes, including the oath of the Fianna.
19. The Riddle Of Rhun is original.
20. Halfwyn At The Birthing Beds is original.
21. Morgana And The Tree Of Corpses is a composite of "magic gone wrong" stories (the Sorcerer's Appentice is the best-known of these), based on the prohibition of not calling up what you cannot put down. Morgana herself is the Arthurian character.
22. The Hound That Ate Dreams is Puss In Boots.
23. Shea And The Deep Roots is Jack And The Beanstalk
24. The Rock Of Avhul is a composite of exodus-stories with other elements.
25. Tatterskin is Bearskin, with elements of Tattercoats and other stories.
25. Ogala And The Hollow Hill is Ali Baba And The Forty Thieves