From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
This one is amazing, truly original. Go use it!
Source Viahorizon
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
A light gray fabric pattern with faded vertical stripes.
Source V. Hartikainen
A seamless pattern made from the gold Penrose triangle by GDJ and the two remixes
Source Firkin
From a drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
Source Firkin
From a design in 'Storia del Palazzo Vecchio in Firenze', Aurelio Gotti, 1889.
Source Firkin
Number 2 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Light gray grunge wall with a nice texture overlay.
Source Adam Anlauf
A seamless pattern formed from a modified version of rwwgub's tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Adapted from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
A new one called white wall, not by me this time.
Source Yuji Honzawa
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
One more sharp little tile for you. Subtle circles this time.
Source Blunia
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Geometric triangles seem to be quite hot these days.
Source Pixeden
This one needs to be used in small areas; you can see it repeat.
Source Luca
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
A bit of scratched up grayness. Always good.
Source Dmitry