You can store the "seed data" any way you like, text files, plists etc. and even in a database (presumably sqlite).
Then when starting up your app, check if the data already exists in your core data store. If not, import the file into your database.
You could also have a preconfigured database and copy that to the application documents directory to make it writable. This is a somewhat more involved approach, as you will have to regenerate this seed database each time your seed data or model changes.