Here's a gradient Background texture file for you to play with.
It was created in Inkscape and then exported as a png.
I've tried to suggest LATE AUTUMN with a hint of frosty gray and very dark leaves mixed with fading leaves of red and brown and orange.
The fires of summer are fading to winter!
How did I do this? First make a square in red or brown
Add the leaves filter. Before or after the leaves filter create a gradient with multiple stops using the wheel or coding the colors whichever you prefer.
Its probably a good look to also use a filter that makes the edges of the square more rougher and assymmetrical like Torn Edges or Watercolor or both or not.