Inspired by this, I came up with this pattern. Madness!
Source Atle Mo
A seamless pattern with green and yellow diagonal lines on top of a white dotted background.
Source V. Hartikainen
From a drawing in 'Friend or Fortune? The story of a strange year', Robert Overton, 1897.
Source Firkin
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
A pale yellow background pattern with vertical stripes. The stripes are partially faded. I think this background image turned out pretty well, especially those faded stripes.
Source V. Hartikainen
Here's a bluish gray striped background pattern for use on web sites.
Source V. Hartikainen
Semi-light fabric pattern made out of random pixels in shades of gray.
Source Atle Mo
Bumps, highlight and shadows – all good things.
Source Badhon Ebrahim
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
The name tells you it has curves. Oh yes, it does!
Source Peter Chon
Remixed from a raster on Pixabay that was uploaded by ArtsyBee.
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
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Fix and cc0 to get the tile this is based on.
Source SliverKnight
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
A simple circle. That’s all it takes. This one is even transparent, for those who like that.
Source Saqib
A light background pattern with diagonal stripes. Here's a simple light striped background for you.
Source V. Hartikainen