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 playful triangle pattern with different shades of gray.
Source Dimitrie Hoekstra
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Here's a quite bright pink background pattern for use on websites. It doesn't look like a real fur, but it definitely resembles one.
Source V. Hartikainen
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
Fix and cc0 to get the tile this is based on.
Source SliverKnight
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Can’t believe we don’t have this in the collection already! Slick woven pattern with crisp details.
Source Max Rudberg
A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
That’s what it is, a dark dot. Or sort of carbon looking.
Source Tsvetelin Nikolov
Prismatic Geometric Pattern Variation 2 With Background
Source GDJ
A chequerboard pattern with a fruit theme. The fruits are from a posting by inkscapeforum.it.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A simple bump filter made upon request at irc #inkscape at freenode. Made a screen capture of the making here: https://youtu.be/TGAWYKVLxQw
Source Lazur URH
A beautiful dark wood pattern, superbly tiled.
Source Omar Alvarado
Scanned some rice paper and tiled it up for you. Enjoy.
Source Atle Mo
Prismatic Geometric Pattern Background 2 No Black
Source GDJ
Number 4 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
A seamless textured paper for backgrounds. Colored in pale orange hues.
Source V. Hartikainen
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin