A seamless gray background texture suitable for use on websites. To me, it has the look of stone. Feel free to modify it to meet your needs (by making it a bit lighter or darker, for example).
Source V. Hartikainen
Psychedelic Geometric Background No Black
Source GDJ
Remixed from a PNG that was uploaded to Pixabay by k_jprather
Source Firkin
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
Zero CC tileable Crackled Cement (streaks) texture, photographed and made by me. CC0
Source Sojan Janso
More carbon fiber for your collections. This time in white or semi-dark gray.
Source Badhon Ebrahim
Thin lines, noise and texture creates this crisp dark denim pattern.
Source Marco Slooten
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Light and tiny, just the way you like it.
Source Rohit Arun Rao
Abstract Ellipses Background Grayscale
Source GDJ
More in the paper realm, this time with fibers.
Source Jorge Fuentes
Dark pattern with some nice diagonal stitched lines crossing over.
Source Ashton
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A repeating background with dark brown stone-like texture and abstract pattern that looks like tree trunks.
Source V. Hartikainen
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
I have no idea what J Boo means by this name, but hey – it’s hot.
Source j Boo
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
From a drawing in 'Hubert Montreuil, or the Huguenot and the Dragoon', Francisca Ouvry, 1873.
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Derived from a drawing in 'The Murmur of the Shells', Samuel Cowen, 1879.
Source Firkin
This one needs to be used in small areas; you can see it repeat.
Source Luca
There are many carbon patterns, but this one is tiny.
Source Designova