T-joint made from unseasoned white oak shipped from Oak-lahoma. We do have trees here. Timbers were full 6x6 so I used a 2 inch tenon. The dovetailed flaired 1/2 inch on each side. I cut 4 slots with a pull saw to within 1 inch of the tenon shoulder and carved (4) 1/4 inch wedges about 6 inches long and the thickness of the tenon riven from white oak on site. The 1 inch peg was riven from unseasoned red oak on site. It split nicely.

I know how to make the T-joint stronger now, but that knowledge will cost some beer.