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
Zero CC tileable dry grass texture, photographed and made by me. CC0
Source Sojan Janso
Real snow that tiles, not easy. This is not perfect, but an attempt.
Source Atle Mo
Pass parameters to the URL or edit the source code variables to configure the graph paper for the division desired.
Source JayNick
This one has rusty dark brown texture.
Source V. Hartikainen
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
Hexagonal dark 3D pattern. What more can you ask for?
Source Norbert Levajsics
Derived from an image that was uploaded to Pixabay by Kaz
Source Firkin
Continuing the geometric trend, here is one more.
Source Mike Warner
A free background image with a seamless texture of cardboard. This texture of cardboard looks quite realistic, especially when is actually tiled.
Source V. Hartikainen
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Beautiful dark noise pattern with some dust and grunge.
Source Vincent Klaiber
It’s like Shine Dotted’s sister, only rotated 45 degrees.
Source mediumidee
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
ZeroCC tileable wood boards texture, photographed and made by me. CC0
Source Sojan Janso
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
A seamless light gray paper texture with horizontal double lines.
Source V. Hartikainen
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
From a drawing in 'La Principauté de Liège et les Pays-Bas au XVIe siècle', Société des Bibliophiles Liégeois ,1887.
Source Firkin
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler