I got the 10 free items from Twisted Metal before starting this quest. Once I checked the "My Quest" screen (after starting the quest) it said I had 13/17 items (?). I finished gathering the free items (including the sofa) and went back to check my item count and it still said 13/17. I cleared my cache, restarted Home, checked the activity board and it now says 3/17. lol, umm..
The posts above you indicated where the others can be found. Also mentioned is the chair that is the next step of the quest that "may" not be free until you have completed the previous step of the quest.
I suggest you pick up the quest before getting these. If you don't, you may need to restart home to get them to register.
Here is a summary: (Yes, it's 18 items - 19 including the blue chair)
I didn't receive the Trophy and have it show complete until I returned to the Mall Lvl-1
Edited by Ir0n, 23 December 2011 - 03:39 PM.
added spoiler button