Luna's lost belongings can be found at the following locations.

In the Clock Tower Courtyard directly in front of the Fountain.
In the Entrance Courtyard. Use Wingardium Leviosa on the broom and sweep the leaves on the right side of the courtyard.
In the Great hall on the table.
In the Library on the table.
In the Viaduct Entrance in front on the bookcase next to the stuttering portrait.