Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
The following repeating website background is colored in a blue gray color and resembles a concrete wall or something similar to it.
Source V. Hartikainen
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
Derived from a PNG that was uploaded to Pixabay by nutkitten
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
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
Heavily remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
8 by 8 pixels, and just what the title says.
Source pixilated
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Geometric Tessellation Pattern 3 No Background
Source GDJ
The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall
These dots are already worn for you, so you don’t have to.
Source Matt McDaniel
A seamless design of flowers remixed from a jpg on Pixabay by Prawny.
Source Firkin
This one needs to be used in small areas; you can see it repeat.
Source Luca
Neat little photography icon pattern.
Source Hossam Elbialy