A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
Light honeycomb pattern made up of the classic hexagon shape.
Source Federica Pelzel
Light gray version of the Binding pattern that looks a bit like fabric.
Source Newbury
Sharp pixel pattern looking like some sort of fabric.
Source Dmitry
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
Prismatic Geometric Pattern Background 2
Source GDJ
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Formed from a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
The classic notebook paper with horizontal stripes.
Source Are Sundnes
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin