Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
A very slick dark rubber grip pattern, sort of like the grip on a camera.
Source Sinisha
A yellow tiled background... Blurriness, bokeh effect and rectangles pattern in one mix.
Source V. Hartikainen
A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
Number 5 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Zero CC tileable Crackled Cement (streaks) texture, photographed and made by me. CC0
Source Sojan Janso
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
This one resembles a black concrete wall when is tiled. It should look great, at least with dark website themes.
Source V. Hartikainen
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Light and tiny, just the way you like it.
Source Rohit Arun Rao
This one is quite simple in design, it consists of vertical stripes layered on top of a seamless texture.
Source V. Hartikainen
One more brick pattern. A bit more depth to this one.
Source Benjamin Ward
As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
You could get a bit dizzy from this one, but it might come in handy.
Source Dertig Media
Prismatic Isometric Cube Extra Pattern No Background
Source GDJ
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A good starting point for a cardboard pattern. This would work well in a variety of colors.
Source Atle Mo
One of the few full-color patterns here, but this one was just too good to pass up.
Source Alexey Usoltsev
Prismatic Chevrons Pattern 5 With Background
Source GDJ