Oak tankards are by far the most popular sort I sell, possibly because Oak is the most 'traditional' wood for tankards. The grain pattern varies emormously, not just from plank to plank but also from one end of a plank to the other and even from one side of the plank to the other side. Sometimes it has lots of swirls and loops, but often the grain is fairly straight. The colour too varies from a pale brown to a mid-brown and some even has a reddish hue. I try as much as possible to match the pattern and colour on each stave.
In the third photograph above, a large and small tankard are shown side by side for comparison.