I used a piece of beech that had some sapwood in it, as it was necessary to get the full size I needed with proper quarter sawn grain and with the grain running in the right direction. The patch in the mouth was my attempt to make up for the relative softness of the sapwood beech. My cruddy photo skills cast some shadows on the mouth, making the gauge lines look huge and deep. They are not this way in person. It works phenomenally well!
I'm not usually a fan of shiny wood planes, but this and my plow are extremely shiny and they look incredible, at least to my eyes.
If you are at all interested in making planes, I encourage you to give it a go. Nothing is more satsifying than using a fine tool that you've made yourself, in your own shop, with your own hands.