A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
Prismatic Curved Diamond Pattern 7 No Background
Source GDJ
Nasty or not, it’s a nice pattern that tiles. Like they all do.
Source Badhon Ebrahim
I guess this is inspired by the city of Ravenna in Italy and its stone walls.
Source Sentel
Prismatic Geometric Tessellation Pattern 2 No Background
Source GDJ
Here's a seamless brown cork board background texture. Feel free to download or reshare if you like.
Source V. Hartikainen
A light gray wall or floor (you decide) of concrete.
Source Atle Mo
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
A repeatable image with dark background and metal grid pattern.
Source V. Hartikainen
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.
Source Josh Green
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
A seamless pale yellow paper background with a pattern of animal tracks.
Source V. Hartikainen
Wild Oliva or Oliva Wilde? Darker than the others, sort of a medium dark pattern.
Source Badhon Ebrahim
A version without colours blended together to give a different look.
Source Firkin
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
Derived from an image that was uploaded to Pixabay by mdmelo.
Source Firkin
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin