Just came across your request for information about Reuben Dawson of Mosby's Rangers

I believe he may be from Rappahannock County (VA) - There is a Dawson listed on the Confederate Monument here without a first name.
In reviewing the Mosby rosters there appears to be only one Dawson, namely Reuben.

I am working on a commemorative CW Trails marker next to the monument as the original text has eroded.

If you have learned other info since your original request I would be interested in learning of it.
My wife and I are compiling a list of all Rappahannock County CW Soldiers.

Best regards

John Tole