Drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i
Source Firkin
A blue gray fabric-like texture for websites. An yet another fabric-like texture. It has subtle vertical and diagonal stripes to it.
Source V. Hartikainen
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
Kaleidoscope Prismatic Abstract No Background
Source GDJ
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
Fix and cc0 to get the tile this is based on.
Source SliverKnight
Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
Number five from the same submitter, makes my job easy.
Source Dima Shiper
This seamless background image should look nice on websites. It has a dark blue gray texture with vertical stripes, it tiles seamlessly and, like all of the background images here, it's free. So, if you like it, take it!
Source V. Hartikainen
We have some linen patterns here, but none that are stressed. Until now.
Source Jordan Pittman
Prismatic Triangular Background Design Mark II 5
Source GDJ
Clean and crisp lines all over the place. Wrap it up with this one.
Source Dax Kieran
Inspired by a drawing seen in 'City of Liverpool', James Picton, 1883.
Source Firkin
A seamless pattern the starting point for which was a 'colour modulo' texture in Paint.net.
Source Firkin
Prismatic Abstract Background Design No Black
Source GDJ
The image depicts a seamless pattern which was made using stripe-like things including borders.I used OCAL cliparts called "Blue Greek Key With Lines Border" uploaded by "GR8DAN" and "daisy border" uploaded by "johnny_automatic".Thanks.
Source Yamachem
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin