The inconsistency of drops frustrates many players of Minecraft. You might expect to receive rotten flesh from a zombie, only to find that nothing drops instead. To avoid the unfairness of the game, download the mod titled Consistent Mob Drops! With this mod, you will know exactly what you will receive for defeating a specific mob.
Mobs and Items:
Zombie — three pieces of rotten flesh.
Creeper — three gunpowder.
Skeleton — three bones and two arrows.
Spider — three strings and two spider eyes.
Villager — one emerald.
Ender Dragon — one pair of elytra.
Before installing the mod in Minecraft, make sure to enable experimental gameplay.