Number five from the same submitter, makes my job easy.
Source Dima Shiper
Seamless Olive Green Web Background Image
Source V. Hartikainen
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Background Wall, Art Abstract, Blue Well & CC0 texture.
Source Ractapopulous
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
From a drawing in 'Picturesque New Guinea', J Lindt, 1887.
Source Firkin
A seamless pattern based on a rectangular tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Prismatic Hexagonalist Pattern No Background
Source GDJ
Inspired by a 1930s wallpaper pattern I saw on TV.
Source Firkin
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Abstract Ellipses Background Grayscale
Source GDJ
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
If you’re sick of the fancy 3D, grunge and noisy patterns, take a look at this flat 2D brick wall.
Source Listvetra
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
It’s like Shine Dotted’s sister, only rotated 45 degrees.
Source mediumidee
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
Awesome name, great pattern. Who does not love space?
Source Nick Batchelor
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
Seamless Background For Websites. It has a texture similar to cork-board.
Source V. Hartikainen
Paper model of a tetrahedron. Modelo de papel de um tetraedro.
Source laobc
This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Zero CC tileable seed texture, edited by me to be seamless from a Pixabay image. CC0
Source Sojan Janso