KeyWe

Collectibles are VERY well hidden throughout this game, and there are 15 in total throughout the 36 main levels.

The first one you can get is the Secret Spice Shaker in Summer 2:

1. In the top left of the screen, find the only blank slip of paper. Pick up the piece of paper to reveal a key.

2. Pick up the key and take it to the blue filing cabinet, to the left of the toaster. Unlock the filing cabinet with the key, and a piece of bread will appear.
Take the bread to the toaster. Using both kiwis, press down on the levers to toast the bread.

3. When the bread is finished toasting, it will pop up. Catch it and bring it to the cassowary food dish at the top of the screen. When the cassowary finishes eating the toast, you'll get the Secret Spice Shaker.