Check your journal when you enter the maze for the first time to see if this quest is auto-assigned. I do not believe I did anything to initiate it.
While in Morrigan's Maze, keep an eye out for mobs dropping the below items. If you collect them and turn them in to Morrigan at the completion of the Maze (or, if you suffer an untimely death) you will complete her collection. These do not need to be turned in all at once, in fact, it will require multiple trips into the maze to find all the items.
Morrigan's 2nd Collection
Morrigan's after even more tat.
- an obsidian shard
- a muddy boot
- a sherd of pottery
- a lithic flake
- a small animal bone
- a half-rotted potato
- a mussel shell
- a chunk of tin ore
- a chunk of copper ore
- a lump of melted bronze
Morrigan's 3rd Collection
Why anyone would want all this is beyond you.
- an ancient tome
* an ethereal tome
- a wind-torn page
- a partially charred scroll
- a worn and battered tome
- a collection of Galen's Treatises
* a leather-bound book of recipes
- a scribbled incantation
- a book entitled, "Beowulf"
- an Ogham inscribed stone
You're beginning to think Morrigan might have a problem.
- an amulet made of st-john's-wort
- an amulet made of benzoin
- an amulet made of camphor
- an amulet made of rue
- an amulet made of citronella
- an amulet made of basil
- an amulet made of mistletoe
- an amulet of bay leaves
- an amulet made of eucalyptus
- a solid gold bulla