As ever open to interpretation, this topic proved a rich source of inspiration. Some chose contrast to mean contrast in texture (rough / smooth, hard / soft), others a contrast in colour or even a contrast in culture. With the unexpected turn in the weather, we added a last minute "snow" submission, a sample of which you can see here. First - some texture.
Hover over or touch a thumbnail to see the picture. On to page two page 3 page 4 page 5 snow
AC

Alister: Two pictures of bark (a popular texture subject). Compare the colours

AC Apa

Alister: A single rose providing a colour contrast

Ann: A simple shot of pebbles, but very effective
APi

Athol: Classic moon shot, showing the craters. Taken using a very strong lens.

Pearls in the snow - contrast of texture
APi

Athol: The power of nature - the amazing shapes and texture of a freezing pond

Fur and bark
CM

Carina: Fallen tree with sawdust

Beautiful picture - spikes of colour, smooth water and leaves, texture of the flowers