Making ItemStacks spawn across a map

Okay, I have a minigame and I need custom items to drop on the ground in my map. Obviously the map isn't the whole world so I need something to check for locations of the builds itself and if there is a block there, spawn an itemstack drop. I hope this doesn't sound too confusing, I just need to scatter my map with drops. Thank you.

I am making a minigame and I need this feature btw.

EDIT by Moderator: merged posts, please use the edit button instead of double posting.