Colored maple leaves scattered on a surface. This is tileable, so it can be used as a background or wallpaper.
Source Eady
Tiny, tiny 3D cubes. Reminds me of the good old pattern from k10k.
Source Etienne Rallion
Washi (和紙?) is a type of paper made in Japan. Here’s the pattern for you!
Source Carolynne
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
This one is quite simple in design, it consists of vertical stripes layered on top of a seamless texture.
Source V. Hartikainen
No idea what Nistri means, but it’s a crisp little pattern nonetheless.
Source Markus Reiter
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
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Prismatic Abstract Line Art Pattern Background 2
Source GDJ