The saying goes: If you don't have samples, create some.
This should be applicable to journalism as well as it is to other fields like design, photography, engineering, programming, etc.
You have to build a portfolio to prove your skill and/or willingness to do something for your dream instead of just sitting there and proclaming 'I wish I could be this or that'. In any other CV you start with listing internships until you can replace them with 'real jobs'. So go with anyhing you have at hand and gradually exchange them with 'professional' pieces as soon as possible.
Here some first-hand/personal experience as reference:
My sister-in-law studied hospital management. She then started off her professional technical-writing carreer by taking on minor freelance jobs, building up her portfolio and is now professionally writing e-books and news-site-articles.
As a carreer entrant (in engineering) I also refered to assignments delivered during studies and personal projects I tried to realize with two of my classmates. This was an opener for many opportunities.
All the best to you!