I found on the LOTRO forums some great information on gathering the Legendary Trait books for minstrels. I'm shamelessly stealing it and reposting it here because it's a great list.
Book Name: Melodies of the Valar
Granted Trait: Rally!
Description: In-Combat Rez
Book Name: The Rising Chord
Granted Trait: Song of the Hopeful Heart
Description: 60 second +hope buff
Book Name: Valour's Marches
Granted Trait: Anthem of the Wizards
Description: Light damage AOE + debuff
Book Name: A Lesson from Lindir
Granted Trait: Fellowship's Heart
Description: Instance cure of fear + fear immunity + HOT
Level 50 class quest
WHere to get the pages
1st 4: Orcs in Dun Covad
Last 4: Wights in Imlad Balcoth - all of them, not just archers
Worldwide random drop off humanoids (aka non-beast/insect) lvl 39+
Melodies of the Valar
1st 4: Morroval in Western Angmar (both outside and inside the cave)
Last 4: Goblins in the MM
All books drop the same as valour's marches pages, but at a reduced rate. I would guess if you have the book for valar or chord the drop rate is around 5% or less, tradeable pages around 2% and books less than 1%. I firmly believe this drop rate increases slightly based on the level of mobs you kill.
Go ye' forth and grind your hearts out friends. Grind grind grind grind grind.