The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
No relation to the band, but damn it’s subtle!
Source Thomas Myrman
A pale orange background pattern with glossy groove stripes.
Source V. Hartikainen
It has waves, so make sure you don’t get sea sickness.
Source CoolPatterns
Light square grid pattern, great for a “DIY projects” sort of website, maybe?
Source Rafael Almeida
Same as Silver Scales, but in black. Turn your site into a dragon with this great scale pattern.
Source Alex Parker
Bumps, highlight and shadows – all good things.
Source Badhon Ebrahim
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
From a drawing in 'Heroes of North African Discovery', Nancy Meugens, 1894.
Source Firkin
A very dark spotted twinkle pattern for your twinkle needs.
Source Badhon Ebrahim
This one is quite simple in design, it consists of vertical stripes layered on top of a seamless texture.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
Retro Circles Background 4 No Black
Source GDJ
Prismatic Snowflakes Pattern 2 No Background
Source GDJ
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
A blue gray fabric-like texture for websites. An yet another fabric-like texture. It has subtle vertical and diagonal stripes to it.
Source V. Hartikainen
The following repeating website background is colored in a blue gray color and resembles a concrete wall or something similar to it.
Source V. Hartikainen
Remixed from an image on Pixabay uploaded by Prawny
Source Firkin
Not so subtle. These tileable wood patterns are very useful.
Source Elemis
Zero CC tileable bark texture, photographed and made by me. CC0
Source Sojan Janso