Remixed from a vector adapted from a jpg on Pixabay. The tile this is constructed from can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
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
A bit of scratched up grayness. Always good.
Source Dmitry
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Use shift+alt+i on the selected rectangle in Inkscape to get the tile this is based on
Source Firkin
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
A seamless pattern of dark bricks. Maybe it's not very realistic, but it looks good in my opinion.
Source V. Hartikainen
Feel free to use this seamless background texture as a background on a web site. It's colored in a light pink color and is seamlessly tile-able.
Source V. Hartikainen
This one is so simple, yet so good. And you know it. Has to be in the collection.
Source Gluszczenko
Pattern Background, Texture, Photoshop Structure style CC0 texture.
Source Darkmoon1968
A heavy dark gray base, some subtle noise and a 45-degree grid makes this look like a pattern with a tactile feel to it.
Source Atle Mo
Alternative colour scheme. 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
The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
Source Firkin
A playful triangle pattern with different shades of gray.
Source Dimitrie Hoekstra
The image depicts a seamless pattern made using a bird's face.
Source Yamachem
Vertical lines with a bumpy, yet crisp, feel to it.
Source Raasa
Used a cherry by doctormo to make this seamless pattern
Source Firkin
Heavy depth and shadows here, but might work well on some mobile apps.
Source Damian Rivas
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
Here's a repeatable texture that resembles a light green concrete wall or something similar.
Source V. Hartikainen