Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
A bit of scratched up grayness. Always good.
Source Dmitry
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
Here's a subtle marble-like background for use on websites.
Source V. Hartikainen
Derived from a JPG that was uploaded to Pixabay by ractapopulous
Source Firkin
This is sort of fresh, but still feels a bit old school.
Source Martuchox
A car pattern?! Can it be subtle? I say yes!
Source Radosław Rzepecki
Derived from an image that was uploaded to Pixabay by Darkmoon1968
Source Firkin
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
This one resembles a black concrete wall when is tiled. It should look great, at least with dark website themes.
Source V. Hartikainen
A free background pattern with abstract green tiles.
Source V. Hartikainen
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
This light background pattern has a texture of "frozen" surface with diagonal stripes. Here's an yet another addition to the collection of free website backgrounds.
Source V. Hartikainen
Zero CC tileable cork floor, photographed and made by me. CC0
Source Sojan Janso
A version without colours blended together to give a different look.
Source Firkin
More tactile goodness. This time in the form of some rough cloth.
Source Bartosz Kaszubowski
Did anyone say The Hoff? This pattern is in no way related to Baywatch.
Source Josh Green
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
This light blue background pattern is quite pleasing to the eye, it consists of a tiny rough grid pattern, which is seamless by design. That's it, if you like the color, you can use this seamless pattern in a web design without making any further modifications to it.
Source V. Hartikainen
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc