A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
A white version of the very popular linen pattern.
Source Ant Ekşiler
A lovely light gray pattern with stripes and a dash of noise.
Source V. Hartikainen
A dark metallic background with a pattern of stamped dots. Here's a dark "metallic" background pattern for you.
Source V. Hartikainen
A gray background pattern with a texture of textile. Suits perfectly for web design.
Source V. Hartikainen
A good starting point for a cardboard pattern. This would work well in a variety of colors.
Source Atle Mo
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Snowflakes Pattern No Background
Source GDJ
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 lot of people like the icon patterns, so here’s one for your restaurant blog.
Source Andrijana Jarnjak
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Utilising a bird from s-light and some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO
A brown seamless wood texture in a form of stripe pattern. The result has turned out pretty well, in my opinion.
Source V. Hartikainen
Light and tiny, just the way you like it.
Source Rohit Arun Rao
The image depicts a seamless pattern made using a bird's face.
Source Yamachem
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Remixed from a raster on Pixabay that was uploaded by ArtsyBee.
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
This background has abstract texture with some similarities to wood.
Source V. Hartikainen
Classic vertical lines, in all its subtlety.
Source Cody L
Seamless Green Tile Background
Source V. Hartikainen
A yellow tiled background... Blurriness, bokeh effect and rectangles pattern in one mix.
Source V. Hartikainen
From a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
A seamless pattern formed from background pattern 102
Source Firkin