Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
The image is a design of blue glass.How about using it as background image?
Source Yamachem
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A seamless web background with texture of aged grid paper.
Source V. Hartikainen
Honestly, who does not like a little pipe and mustache?
Source Luca Errico
Vertical lines with a bumpy, yet crisp, feel to it.
Source Raasa
Zero CC asphalt, pavement, texture, photographed and made by me. CC0 WARNING I FOUND A SEAM ON THIS TEXTURE
Source Sojan Janso
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
The Grid. A digital frontier. I tried to picture clusters of information as they traveled through the computer.
Source Haris Šumić
Seamless pattern inspired by a drawing on Pixabay. To get the tile this is formed from, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
Drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Inspired by this, I came up with this pattern. Madness!
Source Atle Mo
Prismatic Curved Diamond Pattern 6 No Background
Source GDJ
A seamless green background texture. The image is distributed under a Creative Commons License (like all of the images here).
Source V. Hartikainen
Prismatic Chevrons Pattern 5 With Background
Source GDJ
The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
Source Firkin
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
A seamlessly tile-able grunge background image.
Source V. Hartikainen
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Geometric Pattern Background No Black
Source GDJ