A seamless pattern formed from a sports car on clker.com. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Wasn't satisfied with the original's colouring. Too much component transfer and colormatrixes yet the results are lacking a bit. So this time it is a simple black to transparent fade, making it possible remixing easily once there will be other blending modes supported as well. Probably in inkscape 0.92.
Source Lazur URH
Not sure if this is related to the Nami you get in Google image search, but hey, it’s nice!
Source Dertig Media
Zero CC tileable bark texture, photographed and made by me. CC0
Source Sojan Janso
Submitted by DomainsInfo – wtf, right? But hey, a free pattern.
Source DomainsInfo
This one is so simple, yet so good. And you know it. Has to be in the collection.
Source Gluszczenko
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Prismatic Groovy Concentric Background
Source GDJ
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868
Source Firkin
A seamlessly repeating background pattern of wood. The image is procedurally generated, and, I think, it's turned out quite well.
Source V. Hartikainen
Oh yes, it happened! A pattern in full color.
Source Atle Mo
Brushed aluminum, in a bright gray version. Lovely 2X as well.
Source Andre Schouten
There are many carbon patterns, but this one is tiny.
Source Designova
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
More leather, and this time it’s bigger! You know, in case you need that.
Source Elemis
This was formed by distorting an image of a background on Pixabay.
Source Firkin
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
Abstract Tiled Background Extended 11
Source GDJ
The classic 45-degree diagonal line pattern, done right.
Source Jorick van Hees
Like the name says, light and gray, with some small dots and circles.
Source Brenda Lay