I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
Prismatic Polyskelion Pattern No Background
Source GDJ
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
Remixed from a drawing that was uploaded to Pixabay by DavidZydd
Source Firkin
This is sort of fresh, but still feels a bit old school.
Source Martuchox
Seamless Green Tile Background
Source V. Hartikainen
Bright Multicolored Floral Background by Karen Arnold from PDP.
Source GDJ
A re-make of the Gradient Squares pattern.
Source Dimitar Karaytchev
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
An abstract texture of black metal pipes (seamless).
Source V. Hartikainen
From a drawing in 'Hyde Park from Domesday-Book to date', John Ashton, 1896.
Source Firkin
Basket Fibers, Basket Texture, Braid Background style CC0 texture.
Source 1A-Photoshop
Seamless pattern made from a tile that can be obtained in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
This is the remix of "blue wave-seigaiha".The image depicts a seamless pattern of the front upper part of Japanese five yen coin which is used currently.This design represents a rice with ripe golden ears.
Source Yamachem
Dark and hard, just the way we like it. Embossed triangles makes a nice pattern.
Source Ivan Ginev
Sharp diamond pattern. A small 24x18px tile.
Source Tom Neal
Seamless Prismatic Pythagorean Line Art Pattern No Background. A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
This one is amazing, truly original. Go use it!
Source Viahorizon
Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin