I think the stuffed animals should be crafted by the weaver much like the plush rabbits are – the difference would be that each animal uses its appropriate pelt.
The carpenter could carve an entling from an oak log, and likewise the mason could carve the small stone golem from a piece of stone.
As for the monster heads, I reckon the simplest option is to use relevant existing drops to craft them – goblin honour tokens for the goblin head, kobold scout hats for the kobold and so on. I suspect that modifying the existing drop tables for those enemies (to add a trophy as a rare drop) would lead to compatability issues with any other mod that tried to modify the same monsters.
I love the mammoth head and hope we get to see something like it in a mod! The boar’s head has a good balance between cute and intimidating, however I think it’s a little too flat… almost like it’s squashed together. I think that lengthening the face and snout would make it look a bit more like a wild boar and less like a cartoon pig. I also think a small mohawk/mane would help it stand out as a wild boar rather than a domestic pig.