World 2 contains a single Stamp to collect in every level.
This one is hard to miss. The Stamp is right in front of the final path that leads to the flagpole!
When you first start the level, use the GamePad to life the platform under the second set of blocks. Drop inside the hole under the platform.
Super Bell, Fire Flower, or Super Leaf required! When you come across the giant Piranha Plant in the shadows area, drop down into the small hole and break through the wooden crates to find the Stamp.
Mario required! Enter the world and head to the small pond on the right. Hit the Mario switch and the Stamp will be revealed.
Double Cherry required! To the right of the Red Ring is a set of three Question Blocks. Have one of your duplicates stand on the block on the left, then have another hit the same block from below. The block will rise all the way up to the Stamp above.
There will be a section with a metal grate and the Stamp above it. Run to the front and hop up to the Stamp before the screen moves on.
A tent will appear on the world map. Enter the tent to find a Stamp inside!