@CADREAMIN is correct.
Many NMFs are considered for Mork and Trustees scholarships. The invitations to the scholarship weekend arrive with an early acceptance letter in mid-late January, if memory serves. It’s good to go even if you’re guaranteed the 1/2 tuition NMF as you can sometimes be bumped up to a full tuition. The scholarships don’t stack (i.e., you can’t get any more than whatever the maximum single award amount is). Also, the Mork and Trustees (and even the Presidential) carry some prestige and other perks (e.g., honors dorms, etc.). I don’t recall if there are research stipend associated with them as well.
Even if you do not receive an invitation to the scholarship weekend, it may very well be the case that you that you will be admitted during the regular admit cycle and receive the automatic 1/2 tuition NMF (assuming you specify USC as your 1st choice; you have until May 1st to do so).