The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
Alternative colour scheme for the original floral pattern.
Source Firkin
Same as Silver Scales, but in black. Turn your site into a dragon with this great scale pattern.
Source Alex Parker
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
The image depicts a seamless pattern of Japanese Edo pattern called "kikkou-matsu" or "亀甲松" meaning " tortoiseshell-pinetree".The real pinetree is like this: https://jp.pinterest.com/pin/500744052301065077/
Source Yamachem
No idea what Nistri means, but it’s a crisp little pattern nonetheless.
Source Markus Reiter
Inspired by an image that was uploaded to Pixabay by geralt
Source Firkin
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
White circles connecting on a light gray background.
Source Mark Collins
Seamless Dark Grunge Texture. Here's a new grunge texture for use as a background.
Source V. Hartikainen
A seamless striped fabric-like texture colored in a dark reddish brown color.
Source V. Hartikainen
This is a grid, only it’s noisy. You know. Reminds you of those printed grids you draw on.
Source Vectorpile
A frame using leaves from an image that was uploaded to Pixabay by mayapujiati
Source Firkin
It’s okay to be square! A nice light gray pattern with random squares.
Source Waseem Dahman
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Dark pattern with some nice diagonal stitched lines crossing over.
Source Ashton
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Classic vertical lines, in all its subtlety.
Source Cody L
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
I have no idea how to describe this one, but it’s light and delicate.
Source JBasoo
The classic 45-degree diagonal line pattern, done right.
Source Jorick van Hees
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868.
Source Firkin