From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Drawn in Paint.net and vectorised in Vector Magic
Source Firkin
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
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
Coming in at 666x666px, this is an evil big pattern, but nice and soft at the same time.
Source Atle Mo
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
ZeroCC tileable wood boards texture, photographed and made by me. CC0
Source Sojan Janso
Prismatic Groovy Concentric Background 5
Source GDJ
The classic notebook paper with horizontal stripes.
Source Are Sundnes
Found on the ground in french cafe in kunming, Yunnan, china
Source Rejon
From a drawing in 'A Guide to the Guildhall of the City of London', John Baddeley, 1898.
Source Firkin
Prismatic Triangular Background Design Mark II 5
Source GDJ
A seamless pattern the starting point for which was a 'colour modulo' texture in Paint.net.
Source Firkin
Here's a seamless brown cork board background texture. Feel free to download or reshare if you like.
Source V. Hartikainen
Abstract Geometric Monochrome Pattern Prismatic No Background
Source GDJ
A bit like smudged paint or some sort of steel, here is scribble light.
Source Tegan Male
Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A free green background pattern with a pattern of rhombuses on a seamless texture. Feel free to use it as a tiled background image on your web site.
Source V. Hartikainen