How to show contribution items in CiviReports for Contribution Reports
I believe what you are referring to are line items - if the contributions in question are event contributions, then you can use Extended Report - "Participant Line Items" that will allow you to filter by event, otherwise, Extended Report - "Contributions with Price Set Data" should also show you what you need- but it may take a bit of trial and error, i.e. the report offers several grouping options for line items:


Price Field Label    
Price Field Value Label
Line Item Financial Type
Price Field (line item)
Price Field Option (line item)


You'll want to select whatever option(s) you are grouping by as display columns as well as the following columns:


Quantity
Line Total 
Unit Price (if interesting)


E.g. Grouping by Price Field Option (line item) will yield the following:



Hope this helps!
Tamar