Nostalrius Begins - Quality wow vanilla realm (1.12)

according to http://db.vanillagaming.org/?item=10285 the spiders in WPL should have ~18% drop rate. I killed 15 and no drop so Im thinking loot tables must be different here. Does anyone know a good place I could farm some of this?

Shadow silk is item id 10285 - check your link.
I've never set out to farm shadow silk, but 15 mobs is a small sample - you might just be unlucky. There's usually some on the AH if you need it faster. Good luck & happy farming.

shadow silk sells for 60s a piece or so, I think about 12-15 of them drop just in the LBRS Skitterweb Tunnels. It's really not hard to come by. Ironweb is the most valuable variety of spider silk, going at 1g20s if I recall correctly.