Not even 1kb, but very stylish. Gray thin lines.
Source Struck Axiom
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
A seamless pattern of leopard skin. It should look nice as a background element on web pages.
Source V. Hartikainen
A slightly grainy paper pattern with small horizontal and vertical strokes.
Source Atle Mo
This one needs to be used in small areas; you can see it repeat.
Source Luca
This background texture resembles stone. It may be used as a background on web pages or on some of their html elements (header, borders, menu bar, etc.). Just modify it for your needs.
Source V. Hartikainen
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
From a drawing in 'Danmarks Riges Historie af J. Steenstrup, Kr. Erslev, A. Heise, V. Mollerup, J. A. Fridericia, E. Holm, A. D. Jørgensen', 1897.
Source Firkin
Black paper texture, based on two different images.
Source Atle Mo
Based from Design Kindle
A repeating background of thick textured paper. Actually, it turned out to look like something between a paper and fabric.
Source V. Hartikainen
Looks like an old wall. I guess that’s it then?
Source Viahorizon
This is a grid, only it’s noisy. You know. Reminds you of those printed grids you draw on.
Source Vectorpile
Derived from a drawing in 'The Murmur of the Shells', Samuel Cowen, 1879.
Source Firkin
It was called Navy Blue, but I made it dark. You know, the way I like it.
Source Ethan Hamilton
This beige background pattern resembles a concrete wall with engravings or something similar to it.
Source V. Hartikainen
Remixed from a drawing in 'Canadian forest industries July-December', 1915
Source Firkin
Same classic 45-degree pattern, dark version.
Source Luke McDonald
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin