Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
Colourful background achieved with gradient fills.
Source Firkin
Floral patterns will never go out of style, so enjoy this one.
Source Lasma
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A free background pattern with abstract green tiles.
Source V. Hartikainen
Textured Red Brown Plastic, Free Background Pattern. Although there's already enough plastic in our lives, let's bring it to the web too.)
Source V. Hartikainen
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
A nice and simple white rotated tile pattern.
Source Another One
A criss-cross pattern similar to one I saw mown into a sports field.
Source Firkin
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
One can never have too few rice paper patterns, so here is one more.
Source Atle Mo
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A seamless web texture of "green stone".
Source V. Hartikainen
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
The image depicts a Japanese Edo pattern called "kanoko or 鹿の子" meaning "fawn" which has a fur with small white spots.
Source Yamachem
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868
Source Firkin
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo