Indeed there are, 19 altogether with the Ragnarok expansion included. Some of the Easter Egg items the devs included for fun. The full list is:
An Entreaty
Diary of a Teenage Maenad
Form W-900
Gronk's Apology
Kar'tak's Journal
Lamia Grocery List
Letter from Beastman Archer 783
Letter from Troy
Letter to Cleo
Letter to Mummy
Ode to the Night
Recipe for Karkinos Bisque
Report from the Front
The Amazing Artius
The Diary of Sorius
Welcome to Undeath!
Behind the Wall
Actor's Notes
Poet's Jottings
And given that Grava, one of the Grim Dawn devs who also worked on TQ/IT, writes the GD lore notes he may also have written these.