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 slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
Alternative colour scheme for the original floral pattern.
Source Firkin
I guess this is inspired by the city of Ravenna in Italy and its stone walls.
Source Sentel
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
Zero CC tillable hard cover red book with X shape marks. Scanned and made by me.
Source Sojan Janso
Colored maple leaves scattered on a surface. This is tileable, so it can be used as a background or wallpaper.
Source Eady
The texture of this background image has some similarities with leather, and it's colored in a dark brown color. So, if you are looking for a dark brown background image for your website, this may be an option for you.
Source V. Hartikainen
Number 5 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Remixed from a drawing in 'Очерки Русской Исторіи въ памятникахъ быта', Petr Polevoi, 1879.
Source Firkin
On a large canvas you can see it tiling, but used on smaller areas, it’s beautiful.
Source Paul Phönixweiß
This ladies and gentlemen, is texturetastic! Love it.
Source Adam Pickering
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
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
More leather, and this time it’s bigger! You know, in case you need that.
Source Elemis
Don’t look at this one too long if you’re high on something.
Source Luuk van Baars
Sometimes you just need the simplest thing.
Source Fabricio
Zero CC tileable brick texture, photographed and made by me. CC0
Source Sojan Janso
Abstract Tiled Background Extended 8
Source GDJ
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
Nothing like a clean set of bed sheets, huh?
Source Badhon Ebrahim