This area is a simple hill. The other Toad Brigade member are here. There are plants on the ground. Pick them for coins. Go around the corner and walk up the ramp into the hill for the first gem. Go back down the ramp and pick the plants for more coins. Pull up the handle to raise the platform up. There's a ladder so you can return if you go back down. Some of the plants have turnips you can throw. Throw it at the POW Block to clear out the blocks. This will allow you to reach the second gem. Near the gem is a plateau with a Shy Guy on it. Climb up the ladder and pull the plants until you get the pickax. It will start picking at what's in front of you and can destroy bricks, so just move where you want to go. Use it near the gem to get lots of coins. Drop down and break the bricks near the ladder to find a Golden Mushroom. Walk around in front of the ramp that leads to the tower with the Star. Pull the nearby handle so you can reach the Toad Brigade. Approach Blue Toad and he'll give you the third gem. Walk up the ramp to the Star.
Special Challenge: Collect the Gold Mushroom. This will get you a stamp on the page.