As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Prismatic Groovy Concentric Background 2 No Black
Source GDJ
A free seamless background image with abstract texture of green "curtain".
Source V. Hartikainen
This is the remix of "Colorful Floral Pattern Background 3" uploaded by "GDJ". Thanks.
Source Yamachem
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
A grayscale fabric pattern with vertical lines of stitch holes.
Source V. Hartikainen
Submitted by DomainsInfo – wtf, right? But hey, a free pattern.
Source DomainsInfo
Sort of like the back of a wooden board. Light, subtle, and stylish, just the way we like it!
Source Nikolalek
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Nice little grid. Would work great as a base on top of some other patterns.
Source Arno Gregorian
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
This one needs to be used in small areas; you can see it repeat.
Source Luca
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
The starting point for this was a texture drawn with the 'Radial Colors' plug-in in Paint.net.
Source Firkin
Simple combination of stripy squares with their negatively coloured counterparts
Source Firkin
This one is super crisp at 2X. Lined paper with some dust and scratches.
Source HQvectors
This is a seamless pattern which is derived from a flower petal image.
Source Yamachem
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless pattern drawn originally in Paint.net by distorting a slice of background pattern 116 and copying the resulting triangle numerous times.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Inspired by a pattern seen on a public domain image of a very old tile. To get the unit cell, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A light gray fabric pattern with faded vertical stripes.
Source V. Hartikainen