Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
Nothing like a clean set of bed sheets, huh?
Source Badhon Ebrahim
A repeating background with dark brown stone-like texture and abstract pattern that looks like tree trunks.
Source V. Hartikainen
Heavily remixed from a drawing that was uploaded to Pixabay by ractapopulous
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
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
Prismatic Geometric Pattern Background No Black
Source GDJ
Prismatic Abstract Geometric Background 4
Source GDJ
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
With a name like this, it has to be hot. Diagonal lines in light shades.
Source Isaac
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
This one is quite simple in design, it consists of vertical stripes layered on top of a seamless texture.
Source V. Hartikainen
Tiny little flowers growing on your screen. Nice, huh?
Source Themes Tube
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
Derived from an image that was uploaded to Pixabay by pugmom40
Source Firkin
Seamless Prismatic Pythagorean Line Art Pattern No Background. A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
Different from the original in being a simple tile stored as a pattern definition, rather than numerous repeated objects. Hence easy and quick to give this pattern to objects of different shapes. To get the tile in Inkscape, select the rectangle and use shift+alt+i.
Source Firkin
Prismatic Groovy Concentric Background
Source GDJ
Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin