Here is the full list of all 31 Valley trophies - there are 14 bronze, 11 silver, 5 gold and 1 platinum.
Acquire all trophies
Collect all energy upgrades
Find all 8 pages
Complete game without the valley dying
Complete the Astra Facility
Stop the Astra Facility from killing the valley
Defeat the Alpha
Drop down the pit located in Proving Grounds
Complete Smoke Lake
Acquire all upgrades for the L.E.A.F. suit
Collect enough medallions to access all pyramid chambers
Take life from 20 animals
Kill 50 trees
Gain entry to the Sussurian Pyramid
Gain entry through all the acorn doors
Complete the Proving Grounds
Find Virginia’s music box
Complete Camp Henday
Defeat 25 dark creatures
Complete the Soma Reactor
Acquire the Lifeseed
Complete the Soma Facility
Complete Titan Rock
Pacify 10 Amrita Swarms
Collect 100 acorns
Complete Susurrus Valley
Discover the secret Landshark encampment
Revive 100 Trees
Take 10,000 steps
Spend 20 minutes of accumulated time in mid-air
Complete Wendigo Lake