From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Prismatic Abstract Background Design
Source GDJ
Pattern #100! A black classic knit-looking pattern.
Source Factorio.us Collective
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
Number five from the same submitter, makes my job easy.
Source Dima Shiper
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
This background pattern looks like bamboo to me. Feel free to download it for your website (for your blog perhaps?).
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 tile this is formed from can be retrieved in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
This is the remix of "Colorful Floral Pattern Background 3" uploaded by "GDJ". Thanks.
Source Yamachem
A set of paper filters. The base texture is generated the same way, only the compositing mode is varied.
Source Lazur URH
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
Background Wall, Art Abstract, Watercolor Vintage style CC0 texture.
Source Ractapopulous
High detail stone wall with minor cracks and specks.
Source Projecteightyfive
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
Tweed is back in style – you heard it here first. Also, the @2X version here is great!
Source Simon Leo
Prismatic Curved Diamond Pattern 3 No Background
Source GDJ
The act or state of corrugating or of being corrugated, a wrinkle; fold; furrow; ridge.
Source Anna Litvinuk
An abstract Background pattern of purple twisty patterns.
Source TikiGiki
This background pattern contains worn out colorful stripes as a texture.
Source V. Hartikainen
ZeroCC tileable mossy (lichen) stone texture, edited from pixabay. CC0
Source Sojan Janso
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