So I know for sure Jack will give you his head, robe, wand DIY. I think the animals will randonly give you the wall, floor and rug if you give them candy. He gave me a carriage at one point too.
Jack will ask for candy and lollipops at first. If you give him 2 candies he'll give you special stuff (I think this is how I got my carriage) but after 2 candies don't even bother giving him candy, only lollipops. Once you give him 2 candies he'll say somethin like 'I crave lollipops only I must have lollipops' and he'll only give you pumpkin material from then on out.
You give the candy to the animals and they'll randomly give you a table setting, candy set (atleast this is what I got), pumpkin material or a lollipop. If you don't give them candy you get pranked, they won't take it from you kinda like how they did in NL.
You can get more candy from the animals inside their homes. Only 3 animals are inside their house, and you can't just go in and out right on top of each other to the same animal, you gotta have some time between each animal before they will give you candy again. They will give you candy multiple times, but you gotta let some time past between each visit.
In the end I got extra items that I didn't need. And even thou Jack says 'I have a special reward for those who continously give me candy' I'm pretty dang sure he DOESN'T. I gave him 21 lollipops, which would be damn near impossible to give him and for one player to accomplish alone had I not made my alt buy candy plus they candy I got from the animals.