Summit Forest - Northeast Side Collectibles - Part 1

Head north to the hunting lodge and the nearby Hunting Lodge Base Camp. It should be marked on your map since you most likely "discovered" it while hunting Solarii earlier. Pick up more arrows leaning against the tree stump to the left of the campfire.

Climb the stairs to the building. Crack open the salvage crate on the veranda. Then go inside to find a document (2/2), part of the Ancient Scrolls set, plus 2 more bundles of arrows.

Go behind the lodge and climb the stairs to the wolf cave, picking up more arrows and the final mushroom (10/10) for the Red Cap Roundup Challenge. The mushroom is growing on the right side of the stairs. It's pretty obvious, but you can use Survival Instinct to see it more clearly. If you've picked all the other fungi, you'll receive a bonus of 150 XP.

NOTE: Several times it appeared I'd earned 200 XP for this challenge instead of the usual 150. I finally figured out that the game was awarding the challenge points and the 50 XP for finding the cave entrance simultaneously.