Level 1 Presents (Green with Red Bow)

• Energy Potions
• Piles of Snow
• Crystal Shards
• Coins

Level 2 Presents (White with Red Bow)

• Pile of Snow
• Pine Tree Saplings
• Animal Treats
• Fairy Wings

Level 3 Presents (Pink with Red Bow)

• Coins
• Gloom Rat Tail
• Stone Block
• Pine Cone Garland
• Oak Tree Sapling
• Rocks

Level 4 Presents (Blue with Silver Bow)

• Chocolate Bar
• Button
• XP
• Boulders
• Pine Cone Garland
• Cornbread Muffin
• Gloom Wolf Potion

Level 5 Presents (Gold with Gold Bow)

• Sword
• Coins
• XP
• Exploration Crystals
• Whetstone
• Love Potions
• Corn Dogs

There are more presents available in each category, but you'll need to make sure that you open them all before January 4. You'll only need to click on a category of present once to open every single present of that kind in your inventory, resulting in mass explosion of items going into your inventory. It's pretty hard to see what each individual gift contains, but just search your inventory for anything that looks new and unfamiliar and you'll eventually spot all of your new goodies. Merry Christmas!