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
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Colourful background achieved with gradient fills.
Source Firkin
Black And White Floral Pattern Background Inverse
Source GDJ
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
Nice little grid. Would work great as a base on top of some other patterns.
Source Arno Gregorian
Nothing like a clean set of bed sheets, huh?
Source Badhon Ebrahim
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
It was called Navy Blue, but I made it dark. You know, the way I like it.
Source Ethan Hamilton
Sounds French. Some 3D square diagonals, that’s all you need to know.
Source Graphiste
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Could be paper, could be a Polaroid frame – up to you!
Source Chaos
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Zero CC tileable Laminate wood texture, photographed and made by me. CC0
Source Sojan Janso
From a drawing in 'Bond Slaves. The story of a struggle.', Isabella Varley, 1893.
Source Firkin
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
A seamless background texture of old cardboard.
Source V. Hartikainen
Greyscale version of a pattern that came out of playing with the 'slinky' plug-in for Paint.net
Source Firkin
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
Prismatic Geometric Pattern Background
Source GDJ
Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin