Another fairly simple design drawn in Paint.net and vectorized in Inkscape.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Prismatic Polyskelion Pattern No Background
Source GDJ
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
A seamless pattern of dark bricks. Maybe it's not very realistic, but it looks good in my opinion.
Source V. Hartikainen
A grayscale fabric pattern with vertical lines of stitch holes.
Source V. Hartikainen
A background pattern with a look of rough fabric.
Source V. Hartikainen
Prismatic Triangular Background Design Mark II 5
Source GDJ
A background formed from an image of an old tile on the New York Metropolitan Museum of Art website. To get the base tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Here's a bluish gray striped background pattern for use on web sites.
Source V. Hartikainen
A dark pattern made out of 3×3 circles and a 1px shadow. This works well as a carbon texture or background.
Source Atle Mo
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
Little x’es, noise and all the stuff you like. Dark like a Monday, with a hint of blue.
Source Tom McArdle
A blue background wallpaper for websites. It has a seamless texture with vertical stripes. It looks quite nice not only when using as a tiled background on websites, but also on computer desktops.
Source V. Hartikainen
This is a grid, only it’s noisy. You know. Reminds you of those printed grids you draw on.
Source Vectorpile
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
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
This one looks like a cork panel. Feel free to use it as a tiled background on your blog or website.
Source V. Hartikainen
Retro Circles Background 4 No Black
Source GDJ
A version without colours blended together to give a different look.
Source Firkin