Like tuff said, the hidden ones are story trophies. I have to hide them there, but I can post them here.
Homecoming - Complete mission 1: "Homecoming"
The Freightway - Complete mission 2: "The Freightway"
Harvest Season - Complete mission 3: "Harvest Season"
Man vs. Machine - Defeat the mech in "Harvest Season"
The Pipeline - Complete mission 4: "The Pipeline"
The Harder They Fall - Defeat the Apex Warrior in "The Pipeline"
Ballard's Crossing - Complete mission 5: "Ballard's Crossing"
Train Robbery - Complete mission 6: "Train Robbery"
The Pit - Complete mission 7: "The Pit"
Making An Entrance - Detonate the rift bomb in "The Pit"
Ashes - Complete mission 8: "Ashes"
Sever - Complete mission 9: "Sever"
The Source - Complete mission 10: "The Source"
Family Reunion - Meet Logan face-to-face in "The Source"
Rest In Peace, Logan - Complete the campaign on Normal difficulty or higher.
Savior of the Spur - Complete the campaign on Hard difficulty or higher.
Only the Beginning... - Complete the campaign on Mercenary difficulty.