From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Might not be super subtle, but quite original in its form.
Source Alex Smith
A dark brown fabric-like background texture with seamless pattern of winding stripes.
Source V. Hartikainen
A free black metallic background pattern. Here's a new pattern I made that looks metallic.
Source V. Hartikainen
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
One more brick pattern. A bit more depth to this one.
Source Benjamin Ward
Drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Prismatic Abstract Background Design
Source GDJ
More in the paper realm, this time with fibers.
Source Jorge Fuentes
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
A pale orange background pattern with glossy groove stripes.
Source V. Hartikainen
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
White fabric looking texture with some nice random wave features.
Source Hendrik Lammers
Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Wild Oliva or Oliva Wilde? Darker than the others, sort of a medium dark pattern.
Source Badhon Ebrahim
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
The image depicts a seamless pattern of a tortoise in tortoiseshell (hexagon).
Source Yamachem
Remixed from a JPG that was uploaded to Pixabay by susanlu4esm
Source Firkin
This is a seamless pattern of regular hexagon which has a honeycomb structure.
Source Yamachem