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
Background pattern made in "Grunge-Like" style. Available in both SVG and JPG formats. Edit to your needs then click the download button.
Source V. Hartikainen
Sort of like the Photoshop transparent background, but better!
Source Alex Parker
From a drawing in 'Storia del Palazzo Vecchio in Firenze', Aurelio Gotti, 1889.
Source Firkin
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Snowflakes Pattern No Background
Source GDJ
Stefan is hard at work, this time with a funky pattern of squares.
Source Stefan Aleksić
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
Prismatic Snowflakes Pattern 3 No Background
Source GDJ
Remixed from an image on Pixabay uploaded by Prawny
Source Firkin
Gold Triangular Seamless Pattern No Background
Source GDJ
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Found on the ground in french cafe in kunming, Yunnan, china
Source Rejon
I’m starting to think I have a concrete wall fetish.
Source Atle Mo
A criss-cross pattern similar to one I saw mown into a sports field.
Source Firkin
Seamless pattern the basic tile for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
A seamless pattern of "sewn stripes" colored in light gray.
Source V. Hartikainen
From a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
A free pink background pattern.
Source V. Hartikainen
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss