org.bukkit.material
Interfaces 
Attachable
Colorable
Directional
Openable
PressureSensor
Redstone
Classes 
Bed
Button
Cake
Cauldron
Chest
Coal
CocoaPlant
Command
Crops
DetectorRail
Diode
DirectionalContainer
Dispenser
Door
Dye
EnderChest
ExtendedRails
FlowerPot
Furnace
FurnaceAndDispenser
Gate
Ladder
Leaves
Lever
LongGrass
MaterialData
MonsterEggs
Mushroom
NetherWarts
PistonBaseMaterial
PistonExtensionMaterial
PoweredRail
PressurePlate
Pumpkin
Rails
RedstoneTorch
RedstoneWire
Sandstone
Sign
SimpleAttachableMaterialData
Skull
SmoothBrick
SpawnEgg
Stairs
Step
TexturedMaterial
Torch
TrapDoor
Tree
Tripwire
TripwireHook
Vine
WoodenStep
Wool
Enums 
CocoaPlant.CocoaPlantSize