These were my results...
I found that the woven texture of the basket was particularly difficult to capture convincingly - I used Letraset Promarkers, Aquarelle watercolour pencils (and a rubbing with crayon that has gone missing!). I struggled with this one.
The bogwood was also quite tricky. I used pencil, watercolour and a combination of gouache applied with a decorating brush and wax crayon rubbing. Of the three, I like the appearance of the gouache/wax. The rough bristles of the decorating brush came the closest to the texture I was looking for and the colours are the best of the three examples.
Surprisingly the coral was the most interesting and satisfying texture to interpret, despite the piece being almost completely white. Perhaps this meant I had to focus on texture without being distracted by colour. I worked in fineliner pen, a 6H pencil and, to see how a less precise media would work, pastel washed with watercolour. Of thes, I like the pen best because of the intensity of the texture but I think each could be interpreted nicely in stitchwork.
And here are photos of the pieces:
