Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
f you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Zero CC Mossy stone tileable texture, photographed and made by me. CC0
Source Sojan Janso
You could get a bit dizzy from this one, but it might come in handy.
Source Dertig Media
Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Green Web Background, Seamless tile.
Source V. Hartikainen
A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
Remixed from a JPG that was uploaded to Pixabay by susanlu4esm
Source Firkin
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
One more from Badhon, sharp horizontal lines making an embossed paper feeling.
Source Badhon Ebrahim
A lovely light gray pattern with stripes and a dash of noise.
Source V. Hartikainen
A version without colours blended together to give a different look.
Source Firkin
This background texture resembles stone. It may be used as a background on web pages or on some of their html elements (header, borders, menu bar, etc.). Just modify it for your needs.
Source V. Hartikainen
Here's a bluish gray striped background pattern for use on web sites.
Source V. Hartikainen
A textured orange background pattern with vertical stripes.
Source V. Hartikainen
A large (588x375px) sand-colored pattern for your ever-growing collection. Shrink at will.
Source Alex Tapein
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
Background pattern originally a PNG drawn in Paint.net
Source Firkin
New paper pattern with a slightly organic feel to it, using some thin threads.
Source Atle Mo
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin