You can snag them in a whole bunch of places, such as:
-The Swan Islands, from a harvest point on the island with Drongo. It's the middle of the 3 islands.
-Jack Frost's Playground, from the southern most Harvest Point. Jack Frost's Playground is the Winter Island the furthest to the SE.
-Giant's Tabletop, the area to the north of Rolling Hills that you can only access via Dragon. I forget exactly which one, but I think it's the one on top of the stone pillar.
-The Barrens, which is the area directly south of Skull Mountain, that you can only access via Dragon.
You can also steal them from Hyperbore on Billy Goat's Bluff - South, the area around Perdida, which you need the dragon to access.
They also drop rarely off of Web Master on The Spindle, which is an island directly west of Autumnia. --- I kill because I'm weak. Too weak to incapacitate an aggressor without killing them. Killing is easy. Not having to fight is hard.