In Pokemon Emerald, a Starf Berry can be obtained from Scott after getting all the Battle Frontiers Symbols in the Gold Shine.
Now, did you get yours?
If so, did you plant it and let it grow so you can get more of them?
I sure did, and currently, I have 150 Starf Berries in total.
Discuss the mystic Berry!
Note: Starf Berry comes from Starfruit, which is, well, a fruit with a shape of a star.