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
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
The image depicts meshed silhouettes of various things.The original image is an OCAL clipart called "Enter FOSSASIA 2016 #IoT T-shirt Design Contest" uploaded by "openclipart".Thanks.
Source Yamachem
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Neat little photography icon pattern.
Source Hossam Elbialy
Textured Red Brown Plastic, Free Background Pattern. Although there's already enough plastic in our lives, let's bring it to the web too.)
Source V. Hartikainen
The name is totally random, but hey, it sounds good.
Source Atle Mo
Prismatic Groovy Concentric Background 4
Source GDJ
A dark striped seamless pattern suitable for use as a background on websites.
Source V. Hartikainen
A new take on the black linen pattern. Softer this time.
Source Atle Mo
I love these crisp, tiny, super subtle patterns.
Source Badhon Ebrahim
Sharp diamond pattern. A small 24x18px tile.
Source Tom Neal
This background has abstract texture with some similarities to wood.
Source V. Hartikainen
Prismatic Rounded Squares Grid 3 No Background
Source GDJ
More carbon fiber for your collections. This time in white or semi-dark gray.
Source Badhon Ebrahim
A background formed from an image of an old tile on the New York Metropolitan Museum of Art website. To get the base tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
The name tells you it has curves. Oh yes, it does!
Source Peter Chon
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Same classic 45-degree pattern, dark version.
Source Luke McDonald