Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
Could be paper, could be a Polaroid frame – up to you!
Source Chaos
Background Wall, Art Abstract, Blue Well & CC0 texture.
Source Ractapopulous
Might not be super subtle, but quite original in its form.
Source Alex Smith
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Black paper texture, based on two different images.
Source Atle Mo
Based from Design Kindle
A background pattern with blue on white vertical stripes.
Source V. Hartikainen
From an image on opengameart.org shared by rubberduck.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
From a drawing in 'Heroes of North African Discovery', Nancy Meugens, 1894.
Source Firkin
Scanned some rice paper and tiled it up for you. Enjoy.
Source Atle Mo