Farming Wool and SilkFollow

Where can I farm wool and silk cloth easily? I'd prefer a level range of 20-30 thank you.

For Alliance side, the Stockade is a great place for Woolcloth to drop. Many humanoids in the early to mid-20's anywhere will have a chance to drop it as well.

For silk cloth, I'd recommend Gnomeregan (though that's at the high end, if not exceeding your desired level range). Similar to wool cloth, humanoids have a chance of dropping silk cloth, but usually higher level (say, starting in late 20's and going all the way into the 30's). If you can be patient on the Silk Cloth, it drops like crazy in Scarlet Monastery as well, but that's a higher level instance than you're looking for.

Silk - IMO the orcs in wetlands are tightly packed, often come in single pulls, and drop loads of silk and coin for there level. Decent respawn rate and not to populated, and also only ever seen horde there once.