A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
Same as gray sand but lighter. A sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
Little x’es, noise and all the stuff you like. Dark like a Monday, with a hint of blue.
Source Tom McArdle
A simple circle. That’s all it takes. This one is even transparent, for those who like that.
Source Saqib
From a drawing in 'Uit de geschiedenis der Heilige Stede te Amsterdam', Yohannes Sterck, 1898.
Source Firkin
This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda
Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
A seamless pattern based on a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
You could get a bit dizzy from this one, but it might come in handy.
Source Dertig Media
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
No idea what Nistri means, but it’s a crisp little pattern nonetheless.
Source Markus Reiter
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
Prismatic Curved Diamond Pattern 6 No Background
Source GDJ
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Hexagonal dark 3D pattern. What more can you ask for?
Source Norbert Levajsics
Prismatic Snowflakes Pattern No Background
Source GDJ
Clean and crisp lines all over the place. Wrap it up with this one.
Source Dax Kieran
A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
Prismatic Curved Diamond Pattern No Background
Source GDJ
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
A seamless design of flowers remixed from a jpg on Pixabay by Prawny.
Source Firkin