Not even 1kb, but very stylish. Gray thin lines.
Source Struck Axiom
Background Wall, Art Abstract, Watercolor Vintage style CC0 texture.
Source Ractapopulous
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Dark blue concrete wall with some small dust spots.
Source Atle Mo
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
A repeating background with seamless texture of stone. There haven't been any stone-like backgrounds for a while, so I have decided to create one more. The rest can be found in the appropriate category.
Source V. Hartikainen
Prismatic Hexagonalist Pattern No Background
Source GDJ
If you don’t like cream and pixels, you’re in the wrong place.
Source Mizanur Rahman
Drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
A seamlessly tileable pink background texture.
Source V. Hartikainen
I love these crisp, tiny, super subtle patterns.
Source Badhon Ebrahim
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
It’s an egg, in the form of a pattern. This really is 2012.
Source Paul Phönixweiß
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
This background pattern contains a texture of yellow wood planks. I think it looks quite original.
Source V. Hartikainen
Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ