Seamless Wood Pattern #889
 Wood  CC BY-SA 3.0

A seamlessly repeating background pattern of wood. The image is procedurally generated, and, I think, it's turned out quite well.

Source V. Hartikainen

 More Textures
Background pattern 6 #226
 Noise  CC 0

A pattern derived from part of a fractal rendering in Paint.net.

Source Firkin

Vintage pattern 2 #2295
 Yellow  CC 0

Inspired by a pattern seen on a public domain image of a very old tile. To get the unit cell, select the rectangle in Inkscape and use shift+alt+i.

Source Firkin

Background pattern yellow #2025
 Yellow  CC 0

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

Background pattern 274 #2041
 Dark  CC 0

Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.

Source Firkin

Patchwork Quilt Pattern Background #228
 Noise  CC 0

PDP

Source GDJ

Colorful Floral Pattern Background 3-remix #215
 Noise  CC 0

This is the remix of "Colorful Floral Pattern Background 3" uploaded by "GDJ". Thanks.

Source Yamachem

Prismatic Polka Dots Mark II No Background@2X #531
 Noise  CC 0

Prismatic Polka Dots Mark II No Background

Source GDJ

Lined Paper #362
 Stripes  CC BY-SA 3.0

The classic notebook paper with horizontal stripes.

Source Are Sundnes