photoshop change image

Hi

You could do this in Photoshop using the Filter>Other Offset to move the image half across and half down then clone over the edge (repeating as required) to get a tileable pattern.
However, there are better tools for example Adobe now own Substance Alchemist which is designed to produce tileable textures from a 2D image. It produces these not only as 2D patterns but as complete materials with height maps etc. It also has the tools to randomise elements of the image which helps to disguise the joins .

See below screenshot using your image as the basis for the texture (in this forum click on the image to open in a separate window then right click and choose view image to see at full size)

 Maximom, I love the moss, one of my favorite things in our wet country of Oregon. I think this larger picture is just right to make it a lot smaller.  If the original is say 7"X 7" reduce to 3"X3" and see if that works. 

You can free transform to a larger or angled size. I often copy a patch of the moss and then transform it. This is a long-form of moss, so don't compact it too much. You can also copy this picture, paste it on another layer, and then fiddle with it with filters and such. Have fun with it. Best always, JH

The image was just taken too close, so showing more detail. I don't think you can make all the blades smaller, other than duplicating the layer and tiling the layers, but that would show a repeat patten.