Some limbs of trees can be cutting veneers. These disks are called “oysters”. Often the oysters have great character and can show the growth of the tree. You can follow the knots from piece to piece as the little branch enters and exits the larger limb.
Walnut is an excellent wood for oysters. It is relatively stable and the disks can be cut and dried without too many of them splitting apart. Walnut also has a significant contrast between the heartwood and sapwood.
In this piece the walnut branch was about three inches in diameter and I cut cut it on an angle, elongating the sections into ellipses. There were about 60 disks altogether. I put them in four sets spacing out the individual pieces as if they were falling.