Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
This one is so simple, yet so good. And you know it. Has to be in the collection.
Source Gluszczenko
The image is a seamless pattern of a fishnet.
Source Yamachem
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
Abstract Geometric Monochrome Pattern Prismatic No Background
Source GDJ
This was formed by distorting an image of a background on Pixabay.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
You may use it as is, or modify it as you like.
Source V. Hartikainen
A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
Hexagonal dark 3D pattern. What more can you ask for?
Source Norbert Levajsics
More carbon fiber for your collections. This time in white or semi-dark gray.
Source Badhon Ebrahim
Zero CC tileable hard cover red book, scanned and made by me. CC0
Source Sojan Janso
Neat little photography icon pattern.
Source Hossam Elbialy
A seamless background pattern with impressed gray dots.
Source V. Hartikainen
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez
The file was named striped lens, but hey – Translucent Fibres works too.
Source Angelica
Just like your old suit, all striped and smooth.
Source Alex Berkowitz
We have some linen patterns here, but none that are stressed. Until now.
Source Jordan Pittman
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