There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Three shades of gray makes this pattern look like a small carbon fiber surface. Great readability even for small fonts.
Source Atle Mo
A textured blue background pattern with vertical stripes.
Source V. Hartikainen
A colourful background drawn originally in paint.net and vectorised in Vector Magic.
Source Firkin
Prismatic Groovy Concentric Background
Source GDJ
This reminds me of Game Cube. A nice light 3D cube pattern.
Source Sander Ottens
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
From a drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
Source Firkin
Here's a seamless brown cork board background texture. Feel free to download or reshare if you like.
Source V. Hartikainen
Light honeycomb pattern made up of the classic hexagon shape.
Source Federica Pelzel
A fun-looking elastoplast/band-aid pattern. A hint of orange tone in this one.
Source Josh Green
Classy golf-pants pattern, or crossed stripes if you will.
Source Will Monson
A blue background wallpaper for websites. It has a seamless texture with vertical stripes. It looks quite nice not only when using as a tiled background on websites, but also on computer desktops.
Source V. Hartikainen
A textured orange background pattern with vertical stripes.
Source V. Hartikainen