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