Crafting Materials

Crafting materials are items that drop of slain mobs and can be used with the Craft Armor action to create various suits of armor.

Crafting materials counts as its own item category in the Loot options, which allows a player to decide whether to keep any drops found or discard them automatically.

Drop list
Level - Area - Material

Cloth

 * 1-10 - Goldshire(Ally) Trisfal Glades(Horde) - Linen Cloth
 * 11-20 - Westfall(Ally) Silverpine(Horde) - Wool Cloth
 * 21-30 - Duskwood - Silk Cloth


 * 31-40 - Stranglethorn Vale - Mageweave Cloth


 * 41-50 - Blasted Lands - Runecloth


 * 51-60 - Burning Steppes - Felcloth


 * 61-70 - Netherstorm - Netherweave Cloth

80-85 - Twilight Highlands - Embersilk Cloth
 * 71-80 - Ice Crown - Frostweave Cloth
 * 80-85 - Vashj'ir - Embersilk Cloth
 * 85-90 - Pandaria (entire southern island) Windwool Cloth

Leather
80-85 Mount Hyjal - Savage Leather
 * 1-10 - Teldrassil(Ally) Mulgore(Horde) - Leather Scraps
 * 11-20 - Darkshore(Ally) The Barrens(Horde) - Light Leather
 * 21-30 - Ashenvale - Medium Leather
 * 31-40 - Thousand Needles - Heavy Leather
 * 41-50 - Tanaris - Thick Leather
 * 51-60 - Un’Goro Crater - Rugged Leather
 * 61-70 - Zangarmarsh - Knothide Leather
 * 71-80 - Howling Fjord - Borean Leather
 * 80-85 Uldum - Savage Leather
 * 85-90 - Pandaria (entire southern island) Exotic Leather

Ore

 * 1-10 - Dun Morough(Ally) Durotar(Horde) - Copper Ore
 * 11-20 - Loch Modan(Ally) The Barrens(Horde) - Tin Ore
 * 21-30 - Wetlands - Iron Ore
 * 31-40 - Arathi Highlands - Mithril Ore
 * 41-50 - Hinterlands - Truesilver Ore
 * 51-60 - Western Plaguelands - Thorium Ore
 * 61-70 - Hellfire Peninsula - Fel Iron Ore
 * 71-80 - Dragonblight - Saronite Ore
 * 80-85 - DeepHolm - Elementium Ore
 * 85-90 - Pandaria (entire southern island) Ghost Iron Ore

Thanks to http://grindquest.lefora.com/2012/03/20/crafting-items-list/