None of them will give preserves. They will give either steels or cotton I believe. There are currently only 2 campers that will give preserves as rewards which are Jay and Angus, according to this animalcrossing.wikia.com/wiki/Villager_list_(Pocket_Camp)
The cornstalks were the first item I created that actually needed preserves, so I surprisingly had enough, and even now I had enough for the Pizza I just started on. Hopefully this trend continues.