I read Hunger Games last year and I do not remember
Ember,
Willow,
Meadow.
What I associate with:
Ember - colour / rock amber. It is ok name.
Willow - I think that this is just me, but willow in my language is верба (verba), and that also rocket launcher.
Meadow - this is word, not name. It is not even good word name.
Collins - surname.