Here is another interesting glitch I found on the boards about collectables. If you take a kid and bring them up to the burial area, there is a large purple leaf there, kinda up in the 1-2 oclock position. Put the kid so it is "under" that leaf, they sit there for a few seconds to a minute, and then collectables tend to pop up, also mushrooms. When I really want to get some, that is how I force it to happen. It is not 100%, but most times, probably about 80% of the time, it works.