This one is a heavy garnet (or granite) stitch using a wide zig zag. This is really good for filling large areas, like the poppies in my itty bitty landscape. The next one is the same, only a little bit lighter.
It is good for shading and merging different colours.
The next one is also a garnet stitch, however it is bobbin work, working on the bottom of your fabric using the bobbin. a thicker thread (sorry, I had white to hand at the time) is wound on the bobbin and the bobbin tension loosened to compensate. This thread (a no 10 crochet cotton) is at the limit of my bobbin screw, anything larger must be bypassed, which creates a nice mess of moss stitch on the bottom.
Another bobbin technique, is called cable stitch, this is the same as the one above, however it is not a circular stitch
The last stich is another couching stitch, which I first learnt from Quilt in a day. It is called chain stitch
So, there's a headful!