Here is the full list of all 28 Harvest Moon: One World trophies - there are 12 bronze, 8 silver, 7 gold and 1 platinum.
Become friends with someone.
Get the Medallion in Halo Halo
Catch a fish for the first time.
Get the Medallion in Calisson.
Mine ore for the first time.
Chop down a tree for the first time.
Set up your farm for the first time.
Harvest the first crop you grew yourself.
Get the Medallion near your home.
Unlock all achievements.
Catch every type of fish.
Harvest every type of crop.
Harvest every type of flower.
Mine every type of gem and ore.
Cook every type of dish.
Win in Advanced level in every contest, such as the Red Hot Cook-Off and Equestrian Challenge.
Get the Medallion in Pastilla.
Get the Medallion in Lebkuchen.
Get the Medallion in Salmiakki.
Become better friends.
Become friends on a deeper level.
Become more than friends.
Have a wedding.
Have a child.
Find your missing child.
Your child grows up.
Total shipments of more than 1,000,000 G.
Give lots of gifts to the townspeople.