Featured Items can be acessed within the Challenge.

1. Scroll through the Challenge feed to find a Challenge that says 'Featured Items Available' under the Challenge name.
2. Enter the Challenge. 
3. A popup will appear notifying that the Challenge has Featured Items with a purple button that will take you to the list of items.

You can always go back to the Featured Items section by tapping on the small star purple button to the left of the magnifying glass.