Excellent idea! I love stuff like that. Though, I suspect you'll need several mule characters devoted solely to holding all the stuff. There really are A LOT of quest items in just Prophecies, not even considering the other two chapters.
I suspect you could gather all this and still complete quests. Do the quest up to the point you get the goody; put goody in storage (or drop on ground/have a friend hold in pre; ) abandon quest; retake quest and get new goody to complete with.
My list is nowhere near complete, I'm sure, but how about ...
From pre:
tapestry shread
bear pelts
bear cloak
a hunters horn
a purified hunters horn
devourer eggs (already mentioned)
barradin's tithe
the various letters from people
a poisonous stinger (one of my personal favorites)
the three beautiful items, pearl, pendant and feather
From post:
the krytan artifact (the one from Tydus that you take to Serenity)
mossy rocks
cure for ralena
paulus's symbol
the supplies for capt. arne from that sneaky merchant outside Ft. Ranik
both the empty urn and the urn of ashes
aidan's marks (also nice functionality as a place holder when solo trapping)
carlotta's web marks
tattered cape (I've looked many times but I can't find it. Rumors are it's no longer available.

I really wanted to find one, too.)
ruined mantle armors
mysterious message
the seedy heart thing from blood and smoke quest
silver ring
forgotten sword
symon's history of ascalon
That's just the stuff from Chapter 1 that I can think of off the top of my head. It'd be interesting to complile a list of every quest item from each chapter, to see the grand total and for the memories.
I'm working through NF now, and it seems to me I've seen more quest items than I did in Factions but less than Prophecies. I don't have many memorized yet, but these spring to mind.
The vase and feather things from the orchard mission
juicy heket legs
Good luck with your collection!
Luny