I found out about a second place to farm flax seed last night, so I thought I'd share, along with the first place a lot of people already know about.
The first place is in Verdant Brink, you basically just jump down north of the Jaka Itzel Waypoint - Northeast by the frogs - and fall/glide until you get to a little glade at the bottom, underneath tree roots, and farm flax there. I've got my 10 characters stationed there for daily farming. You can even bring your lower level characters there by way of the Lost Precipice (Gasicioch Na Rall ) guild hall. The way you do this is by bringing your character to the Na Rall guild hall using the guild menu - there is a guild hall button there - exit out the entrance to Verdant Brink. Once out, you should automatically get the first waypoint in the zone - to the east - and from there is a pretty easy trip NW up to where the farming is. Below is a youtube video the shows the way from the waypoint.
The second place is in Tangled Depths, found out about it last night talking to someone by the Verdant Brink farm. Below is the video I followed, and on my way up I noticed an easy to get hero point commune and mastery point chest. When you get up to where the flax seeds are, there are a bunch of electric wyvern in the area and some modrem, so be prepared the fight. There are also two chests there that give Empyreal Fragments, ley line crystals and random loot, just look around for them.
But, why flax seeds, you ask? There are many uses for it right now. It's one of the things we need to help grow the guild hall - can be crafted into vials of linseed oil that are needed, which in turn can be used to make kegs. They are also an ingredient needed for the new crafting profession, Scribe - which also helps the guild by building siege and buffs. You can donate seeds, oil, and/or kegs to Fog if you'd like to help out. Also, because there are lot of people needing this for guilds and scribing right now, it is worth a fair amount in the trading post if you'd like some more gold in your coffers.
Hope this helps someone that didn't' already know about these areas. Please feel free to share any other farming areas that you know of.