You can see an overview of all the attachments and samples added to a project

The attachments tab within the project level aggregates all attachments added to any level within that project (Folders, Experiments...). You may clearly view the attachments' full name and to where was this file attached to within the project's hierarchy:

Similarly, the samples tab allows to see all the samples added to all experiments in the project. You can export the list to a .csv file and use this information to calculate project costs for example.