Here is the full list of all 15 The Magnificent Trufflepigs achievements.
Found all treasures
Found treasure after choosing to detect for longer during Day 5
Found treasure after choosing to detect for longer during Day 4
Looked at the Drop Dead Fred graffiti
Looked at the Graveyard
Found treasure after choosing to detect for longer during Day 3
Found 25 unique treasures
Looked at the rescue copter
Looked at the hang-glider
Found treasure after choosing to detect for longer during Day 2
Found 10 unique treasures
Looked at the hot air balloon
Looked at the wind turbines
Found treasure after choosing to detect for longer during Day 1
Found the first treasure