The resin drops in Central Artery Valley in the Enigma Forest.
The blue dots on Dovves Map show the tree spawn locations.
Enigma Tree and Enigma Roots spawn near the
tall blue rocks that dot the forest in clearings that look
like crop circles on your map/different shapes/circles and triangles.
Killed an Engima Tree at 1475 X 1290
it spawned next to the blue rock here.
EDIT: This just in from cdiver73
"another spawn of trees for resin found.
DAV behind Lamb. 3-4 trees. same spawn rate. good for omnis cause Lamb omni and dont attack on sight."

No resin dropped. Green mob easy to solo.
EDIT: Spawnn time is 30-120 mins give or take.
- Regards, the Ed. ( Spawn seems completely random, inc. the amount that spawn. )
Already camped, some here 5 hours and no drop.
Some first kill getting it.
Seems to be next big choke point.
Added the next morning:
Logged in at 8 a.m. my time near this blue stone above.
FOUR trees were there. One dropped the resin!
Added by the Editor: "It's in the Enigma Forest in CAV, drops from Enigma Trees. Pretty obvious it was going to be there, hardly worth being a secret. May drop from other mobs, not sure. I just turned up, killed one, looted resin, left "
- Shewilda
"Well it is there, but spawn rate sucks BAAAAAAAAAAAADDDDDDDDDDDDDDDDDDDD! Also drop rate sucks BAAAAAAAAADDDDDDDDDDDDD! So if you got it on your first try you are VEEEEEEEEERRRRRRRRRRRRRRRRRRRRY lucky. Im almost four hours into campin and only killed 4 of em. This falls into the camping category that was defined by Gaute, so maybe a change??"
- Selyana
"10 kills in hmm what, 4-5 hours now... not a single drop.. Seems like noone has been able to get a drop in the last 4 hours. At least thats what people I meet down here in CAV are saying.... Yay for rare drops..."
- Hratgard
Your next camp-a-quest begins 