Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
Prismatic Geometric Pattern Background 2
Source GDJ
This seamless light brown background texture resembles a wallpaper with vertical stripes. One way to use it is as a tiled background on web sites.
Source V. Hartikainen
Your eyes can trip a bit from looking at this – use it wisely.
Source Michal Chovanec
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
Three shades of gray makes this pattern look like a small carbon fiber surface. Great readability even for small fonts.
Source Atle Mo
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Not the most creative name, but it’s a good all-purpose light background.
Source Dmitry
Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
Zero CC tileable seed texture, edited by me to be seamless from a Pixabay image. CC0
Source Sojan Janso
Formed by distorting the inside front cover of 'Diversæ insectarum volatilium : icones ad vivum accuratissmè depictæ per celeberrimum pictorem', Jacob Hoefnagel, 1630.
Source Firkin
This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO
This makes me wanna shoot some pool! Sweet green pool table pattern.
Source Caveman
From a drawing in 'Less Black than we're painted', James Payn, 1884.
Source Firkin
Pixel by pixel, sharp and clean. Very light pattern with clear lines.
Source M.Ashok
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
This one resembles a black concrete wall when is tiled. It should look great, at least with dark website themes.
Source V. Hartikainen
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
I have no idea how to describe this one, but it’s light and delicate.
Source JBasoo
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ