Northern Cloth Scavenging is a skill learned from completing a quest or from [A Guide to Northern Cloth Scavenging] at roughly skill level 325 to 350, that allows a tailor to loot extra cloth off of Northrend mobs.
Source
Complete 
[??] Cloth Scavenging quest (costs 5
) from one of the following Tailoring trainers:
Charles Worth in Dalaran.- Darin Goodstitch at Valiance Keep.
- Benjamin Clegg at Valgarde.
- Alexandra McQueen at Vengeance Landing.
- Raenah at Warsong Hold.
Or, learn it from [A Guide to Northern Cloth Scavenging] which is random drop from a Northrend boss.
