Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
Smooth Polaroid pattern with a light blue tint.
Source Daniel Beaton
From a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Hypnotic Pattern 2 No Background
Source GDJ
An abstract Background pattern of purple twisty patterns.
Source TikiGiki
Prismatic Hexagonalist Pattern No Background
Source GDJ
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
Redrawn based on a drawing in 'По Сѣверо-Западу Россіи' Konstantin Sluchevsky, 1897.
Source Firkin
This one has rusty dark brown texture.
Source V. Hartikainen
Prismatic Geometric Pattern Background 2
Source GDJ
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Zero CC Mossy stone tileable texture, photographed and made by me. CC0
Source Sojan Janso
After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers