Confession: I think I accidentally miscounted, and actually have 29 unattributed coins in the lot (plus 3 attributed, and 1 with attribution on holder).
As such, I have three options: 1) post the attribution-on-holder one as number 30 once I get it out of the holder, 2) post one of the attributed coins under number 30 as a puzzle for CCF to figure out, or 3) stop at 29/30 and never post any number 30 at all.
Which would you prefer?
Anyway, the coin...

23 mm, 4.79 grams.
The seller said it's Julia Domna, and the portrait looks about right, but "Augusta Julia" is pretty generic, and any further obverse qualifiers (if there were any) are off flan.
[EDIT: fixed title to add ID.]