I have been playing with Inkscape to create some backgound designs. Here are some if you like to use them. They are in png (portable network graphics) format.
They are in original SVG (Scalable Vector Graphics). I can’t upload them here, since they are not recognised as media file, I think. I can email them if you want.
You should use them in your image editing program to lay them repeatedly and create a pattern.
You can get variations by changing colour, filling colour, blurring or changing transparency.