As part of its big Halloween push, FrontierVille has released new Trick or Treat collections, which can be fulfilled by visiting neighbors and then deciding to 'Trick' or 'Treat' one of their virtual family members. Depending on the action you choose, you have a chance of scoring loot for one of these collections. When complete, they can be redeemed for a cool costume for your frontiersman/woman.
Here's a list of the items you'll need to collect (and hints on how to collect 'em):
Trick Collection ('Trick' a neighbor)
Jar o' Grits
Flaming Bag o' Poo
Treat Collection ('Treat' a neighbor)