First I wrapped the pebble in a piece of batting.
As the left side of the pebble is a bit concave I folded the batting there a few times double. Than I basted the sides of the batting.
For the bottom I cut a piece of turqoise fabric and a piece of an old sheet and basted them on the batting.
Than the top fabric was cut into the correct size.
I folded the seam inwards and sewed it on the bottom fabric. As I wanted there was as little visible of the bottom fabric as possible, the sewing line is almost at the bottom of the pebble. However this results in a little wrinkling at the seam. This doesn't really bother me. The eye is caught by the top of the pebble.
Sideview from the other side