This one is amazing, truly original. Go use it!
Source Viahorizon
An abstract texture of water. It's not perfect, but will do. You may download if you like it.
Source V. Hartikainen
Prismatic Abstract Geometric Background 5
Source GDJ
The basic shapes never get old. Simple triangle pattern.
Source Atle Mo
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
This light blue background pattern is quite pleasing to the eye, it consists of a tiny rough grid pattern, which is seamless by design. That's it, if you like the color, you can use this seamless pattern in a web design without making any further modifications to it.
Source V. Hartikainen
You know, tiny and sharp. I’m sure you’ll find a use for it.
Source Atle Mo
From a drawing in 'Royal Ramsgate', James Simson, 1897.
Source Firkin
A textured blue background pattern with vertical stripes.
Source V. Hartikainen
Number 4 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Derived from an image that was uploaded to Pixabay by Kaz
Source Firkin
You know I’m a sucker for these. Well-crafted paper pattern.
Source Mihaela Hinayon
Dark Tile-able Grunge Texture. I think this texture can be classified as grunge. It's free and seamless, as always.
Source V. Hartikainen
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
Alternative colour scheme for the original floral pattern.
Source Firkin
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Formed from decorative divider 184 in paint.net. Vectorised with Vector Magic.
Source Firkin
The classic 45-degree diagonal line pattern, done right.
Source Jorick van Hees
From a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
One can never have too few rice paper patterns, so here is one more.
Source Atle Mo
Retro Circles Background 5 No Black
Source GDJ