A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
This is the remix of "Background pattern 115" uploaded by "Firkin".Thanks.
Source Yamachem
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers
I love these crisp, tiny, super subtle patterns.
Source Badhon Ebrahim
Inspired by a drawing in 'Kulturgeschichte', Freidrich Hellwald, 1896.
Source Firkin
A background formed from an image of an old tile on the New York Metropolitan Museum of Art website. To get the base tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A classic dark tile for a bit of vintage darkness.
Source Listvetra
This seamless pattern consists of a blue grid on a yellow background.
Source V. Hartikainen
A free seamless texture of reptile skin colored in a dark brown color. As always, you may use it as a repeated background image in your web design works, or for any other purposes.
Source V. Hartikainen
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
A seamlessly tile-able grunge background image.
Source V. Hartikainen
Remixed from an image that was uploaded to Pixabay by CatherineClennan
Source Firkin
Here I have tried to create something that would look like maple wood. Not sure how well it's turned out, but at least it looks like wood.
Source V. Hartikainen
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez
From a drawing in 'La Principauté de Liège et les Pays-Bas au XVIe siècle', Société des Bibliophiles Liégeois ,1887.
Source Firkin
A new take on the black linen pattern. Softer this time.
Source Atle Mo