Lost Sentinel's Pouch
The Lost Sentinel's Pouch is found in a hollowed-out tree at [56.4, 49.3] west of Raynewood Retreat in Ashenvale. The pouch contains 
[Music Roll: Magic] for players who have completed 
[40] Bringing the Bass.
From Raynewood Tower south of Raynewood Retreat, return to the main east-west road and head west 100 yards or so to find a small dirt path leading north (there's a bench with an open book and a bird bath nearby at [56.6, 59.4]). Run north-northwest along the path, then keep running north-northwest up the hill (don't follow the path when it curves west). When it looks like it's impossible to run further north (at roughly [55.6, 51.1], there's an exposed root and a few Elder Ashenvale Bears), turn right (to the east) to spot the path, which circles uphill counterclockwise.
Patch changes
Patch 6.1.0 (2015-02-24): Added.