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 pale olive green background with a seamless texture.
Source V. Hartikainen
Seamless pattern formed from a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
This one is so simple, yet so good. And you know it. Has to be in the collection.
Source Gluszczenko
ZeroCC tileable moss texture, photographed and made by me. CC0
Source Sojan Janso
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A new one called white wall, not by me this time.
Source Yuji Honzawa
A tile-able background for websites with paper-like texture and a grid pattern layered on top of it.
Source V. Hartikainen
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
This seamless light brown background texture resembles a wallpaper with vertical stripes. One way to use it is as a tiled background on web sites.
Source V. Hartikainen
Luxurious looking pattern (for a T-shirt maybe?) with a hint of green.
Source Simon Meek
Prismatic Geometric Tessellation Pattern No Background
Source GDJ
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Prismatic Chevrons Pattern 5 With Background
Source GDJ
Prismatic Abstract Line Art Pattern Background
Source GDJ
Number five from the same submitter, makes my job easy.
Source Dima Shiper
Clean and crisp lines all over the place. Wrap it up with this one.
Source Dax Kieran
Colour version of the original pattern.
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
More carbon fiber for your collections. This time in white or semi-dark gray.
Source Badhon Ebrahim
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Remixed from a raster on Pixabay that was uploaded by ArtsyBee.
Source Firkin