Little Knobs@2X #311
 Light  CC BY-SA 3.0

White little knobs, coming in at 10x10px. Sweet!

Source Amos

 More Textures
Fake Brick #358
 Dark  CC BY-SA 3.0

Black, simple, elegant, and useful.

Source Marat

Concrete Wall 2@2X #80
 Wall  CC BY-SA 3.0

A light gray wall or floor (you decide) of concrete.

Source Atle Mo

Pattern generator #161
 Noise  CC 0

A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.

Source Lazur URH

Vintage tile background #2248
 Brown  CC 0

A background formed from an image of an old tile on the New York Metropolitan Museum of Art website. To get the base tile, select the rectangle in Inkscape and use shift-alt-i.

Source Firkin

Black Mamba@2X #58
 Dark  CC BY-SA 3.0

The name alone is awesome, but so is this sweet dark pattern.

Source Federica Pelzel

Colorful Paw Prints Pattern Background #260
 Noise  CC 0

pixabay.

Source GDJ

Background pattern 258 (colour) #2134
 Red  CC 0

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

Prismatic Geometric Pattern Background 2 #409
 Noise  CC 0

Prismatic Geometric Pattern Background 2

Source GDJ

Mosaic Gems Background@2X #527
 Noise  CC 0

Mosaic Gems Background

Source GDJ

Zig-zag pattern 4 #2415
 Grid  CC 0

A seamless pattern based on a rectangular tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.

Source Firkin

Background pattern blue #1940
 Blue  CC 0

Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady

Source Firkin

Tessellation 16 #2215
 Yellow  CC 0

The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.

Source Firkin

Background pattern 112 #263
 Fabric  CC 0

A seamless pattern with a unit cell drawn as a bitmap in Paint.net and vectorized in Vector Magic.

Source Firkin