You may use it as is, or modify it as you like.
Source V. Hartikainen
Sometimes you just need the simplest thing.
Source Fabricio
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
A seamless canvas texture for using as background on websites. Colored in pale tones of brown.
Source V. Hartikainen
A seamless pattern formed from a tile made from page ornament 22. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
The image depicts a seamless pattern of Japanese Edo pattern called "kikkou-matsu" or "亀甲松" meaning " tortoiseshell-pinetree".The real pinetree is like this: https://jp.pinterest.com/pin/500744052301065077/
Source Yamachem
A comeback for you: the popular Escheresque, now in black.
Source Patten
Prismatic Abstract Geometric Background 4
Source GDJ
From a drawing in 'La Principauté de Liège et les Pays-Bas au XVIe siècle', Société des Bibliophiles Liégeois ,1887.
Source Firkin
This makes me wanna shoot some pool! Sweet green pool table pattern.
Source Caveman
A seamless pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Prismatic Hypnotic Pattern No Background
Source GDJ
The image depicts a seamless pattern of a Japanese family crest called "chidori" in Japanese .A chidori in Japanese means a plover in English.
Source Yamachem
ZeroCC tileable stone texture, edited from pixabay. CC0
Source Sojan Janso
Black version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Thin lines, noise and texture creates this crisp dark denim pattern.
Source Marco Slooten
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein