A seamless pattern the starting point for which was a 'light rays' rendering in Paint.net.
Source Firkin
Classic 45-degree pattern, light version.
Source Luke McDonald
Here's a repeatable texture that resembles a light green concrete wall or something similar.
Source V. Hartikainen
From a drawing in 'Picturesque New Guinea', J Lindt, 1887.
Source Firkin
Zero CC tileable cork floor, photographed and made by me. CC0
Source Sojan Janso
A comeback for you: the popular Escheresque, now in black.
Source Patten
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Classy golf-pants pattern, or crossed stripes if you will.
Source Will Monson
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
The image depicts the Japanese Edo pattern called "seigaiha" or "青海波" meaning "blue -sea- wave".I hope it's suitable for the summer season.
Source Yamachem
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
Looks like an old wall. I guess that’s it then?
Source Viahorizon
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
You know I love paper patterns. Here is one from Stephen. Say thank you!
Source Stephen Gilbert
Prismatic Curved Diamond Pattern No Background
Source GDJ