Poppy seeds

I was doing some tidying in the garden today, and dropped some poppy seed pods on the concrete, resulting in a pile of tiny seeds.  I took a photo of these, to show the large number, but when I came to look at the photos on the computer, I thought that the seeds were interesting to look at. I wonder what the function is of the little dimples.
In extras, I've added a more distant shot of the seeds, and also a shot of some ripe brambles.  We saw some yesterday, and were saying that they are extremely early for here - then this morning, the BBC had a piece about the "false autumn".