Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A bit strange this one, but nice at the same time.
Source Diogo Silva
The tile this is based on was adapted from an image that was uploaded to Pixabay by frolicsomepl. It can be had in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
A repeating background for websites with a texture of black groove stripes.
Source V. Hartikainen
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A fun-looking elastoplast/band-aid pattern. A hint of orange tone in this one.
Source Josh Green
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
A nice one indeed, but I have a feeling we have it already? If you spot a copy, let me know on Twitter.
Source Graphiste
A frame using leaves from an image that was uploaded to Pixabay by mayapujiati
Source Firkin
In the spirit of WWDC 2011, here is a dark iOS inspired linen pattern.
Source Atle Mo
Just a nice looking textured pattern with faded blue stripes. Well, that's it for today... one background a day, as usual.
Source V. Hartikainen
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin
The edges of all the red objects line up either vertically or horizontally, but it doesn't appear so. Made from a square tile that can be got by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
The act or state of corrugating or of being corrugated, a wrinkle; fold; furrow; ridge.
Source Anna Litvinuk