Herb Pouch

The Herb Pouch is a herb bag that will only hold herbs and nothing else in it.

Source
Unlike the other, larger herb bags, this bag is not crafted and can instead be bought from vendors:

Alliance

 * Chardryn in Darnassus
 * Eldraeith in Stormwind
 * Gwina Stonebranch in Ironforge
 * Uma Bartulm in Theramore Isle, Dustwallow Marsh

Horde

 * Botanist Tyniarrel in Saltheril's Haven, Eversong Woods
 * Katrina Alliestar in Undercity
 * Selina Weston in Brill, Tirisfal Glades
 * Zeal'aya in Orgrimmar

The bag costs to buy.