Hello! So my last name is Vaughan, pronounced \Von\. Could this last name possibly have roots in an aspirated form of Bann or Boyne? I know the the genitive form of proper names get aspirated so it would make sense. Also, I know that there were a lot of silent "gh" in older Irish that have since been done away with. Furthermore, people have been thinking I've been saying "Baughan" my whole life when I say my last name, so it would be awesome if this had some reason to it.

Thanks!!

It's a Welsh surname.

Either anglicized Welsh (bychan, fychan = small) or anglicized from Irish Ó Mocháin (Mochán = the early one).
Acc. to Patrick Woulfes "Irish names and surnames" most Irish Vaughans aren’t of Welsh* origin, so muintir Uí Mhocháin.

(* There is a Gaelicized version of (orig. Welsh) Vaughan: Uachan.)

There is (afaik) no tradition in Ireland to derive surnames from rivers.