Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
Derived from an image that was uploaded to Pixabay by Kaz
Source Firkin
Can never have too many knitting patterns, especially as nice as this.
Source Victoria Spahn
Number 4 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
Zero CC plastic pattern texture, photographed and made by me. CC0 *Note, this texture was on the perfectly smooth surface of a plastic shovel scraper, not sure how to call it. Plz coment if you know what its called.
Source Sojan Janso
Derived from an image that was uploaded to Pixabay by darkmoon1968
Source Firkin
A comeback for you: the popular Escheresque, now in black.
Source Patten
Prismatic Curved Diamond Pattern 8 No Background
Source GDJ
This is so subtle: We’re talking 1% opacity. Get your squint on!
Source Atle Mo
Simple combination of stripy squares with their negatively coloured counterparts
Source Firkin
As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
Remixed from a raster on Pixabay that was uploaded by ArtsyBee.
Source Firkin
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
This could be a hippy vintage wallpaper.
Source Tileable Patterns
Dark pattern with some nice diagonal stitched lines crossing over.
Source Ashton
Inspired by a drawing seen in 'City of Liverpool', James Picton, 1883.
Source Firkin
Tweed is back in style – you heard it here first. Also, the @2X version here is great!
Source Simon Leo
A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
Super subtle indeed, a medium gray pattern with tiny dots in a grid.
Source Designova
ZeroCC tileable wood boards texture, photographed and made by me. CC0
Source Sojan Janso