Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
Prismatic Hexagonalist Pattern No Background
Source GDJ
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Prismatic Geometric Pattern Variation 2 With Background
Source GDJ
Never out of fashion and so much hotter than the 45º everyone knows, here is a sweet 60º line pattern.
Source Atle Mo
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
A seamless pattern formed from cross 4. To get the original tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
The tile can be had by selecting the rectangle in Inkscape and using shift+alt+i. Remixed from a drawing in 'Flowers of Song', Frederick Weatherly, 1895.
Source Firkin
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Inspired by a pattern I saw in a 19th century book. This seamless pattern was created from a square tile. To get the tile, select the pattern in Inkscape and use shift+alt+i.
Source Firkin
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
From a drawing in 'Picturesque New Guinea', J Lindt, 1887.
Source Firkin
CC0 and seamless wellington boot pattern.
Source SliverKnight
A lot of people like the icon patterns, so here’s one for your restaurant blog.
Source Andrijana Jarnjak
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
Classic vertical lines, in all its subtlety.
Source Cody L
Background formed from the original with an emboss effect
Source GDJ
Super subtle indeed, a medium gray pattern with tiny dots in a grid.
Source Designova
Colour version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
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