A great place I found was in the Spore Hollow in Jugner. Attack one funguar then run around and link the rest. By the time u have them all you'll be close to 100tp and can AoE WS almost all to death. very easy.
The only problem with Kirra' advice is that the drop rate of loot is greatly lowered if you kill mobs with an AoE attack of any kind, be it ws or magic.
Spore Hollow is a good place to farm, but you'll see better results if you don't link them all and AoE.
Sleepshrooms can NPC with Gourmet Quest in Basty. Salimah - Bastok Markets (L-8) will give you 200 per. (According to ffxiclopedia). The drawbacks are that you have to zone to repeat quest and it is dependant on time of day. If you ignore the time you can still NPC it here for 100. Presumably a way to increase fame/reputation also.
I found that farming Sleepshrooms from Exorays at Crawlers' Nest very convenient because of their 100% drop rate. Can easily switch between the three Exoray camps as the mobs respawn. Just be mindful of other players who level off them for GoV pages.
