You can unlock secrets with them:
Mal0: Enderman + carved pumpkin head + skeleton background + making enderman cum
Hornet: Bee + carved pumpkin head + skeleton background + making bee cum
The lamb: Sheep + carved pumpkin head + skeleton background + making sheep cum
Pumcat: Craftable pumpkin girl + carved pumpkin head + skeleton background + making it cum
Craftable pumpkin girl: 8 pumpkins + 1 shears