Materials

You can use them everywhere you must specify a material for an item and NOT a block. Only simple materials work for blocks.
If the material/block is not appearing, then make sure that there isn't an other name.

Simple Materials (Stone, Chest, Beacon, ...)

Usage: <Material>[:Data]
Example: dirt
or: stone:1
or: log:3

List with available materials

Creature Spawner/Egg

Usage: <Material>:<Entity Name>
For example: mob_spawner:creeper
or: moster_egg:chicken

List with available entity types

Player Skulls

Usage: <Material>:<Player Name>
Example: skull:Notch

Potions

Usage: <Material>:<Effect Name>:<Duration>:<Amplifier>
For example: potion:jump:1200:0 (LVL 1 and available for 60 seconds)

List with available potion types

Dyed Leather Armor

Usage: <Material>:<Hex Color>
Example: leather_chestplate:#e542ff
May won't work for ingame players as it may get overwritten with the color of their team.