The Benson (New England) tartan (No. 6465 in the ITI) was designed by Bensons in Vermont, for all of the family name.

There is no "Benson Clan." Because there is no clan cheif, or otherwise head of family, there is no one with the authority to say what is and is not the proper tartan for the family.

Like many Scottish names who have no tartan of their own, and no clan affiliation, people of the name have modernly designed a tartan for the name. You are free to wear it if you wish!

The Roxburgh district tartan would reflect the area in Scotland where the name was from (apparantly, I haven't done any research on the Bensons myself, so I'm just assuming that this link is accurate).

Aye,
Matt