Background pattern 19 (black) #203
 Dark  CC 0

A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.

Source Firkin

 More Textures
blocky filter pack 2 #158
 Noise  CC 0

Wasn't satisfied with the original's colouring. Too much component transfer and colormatrixes yet the results are lacking a bit. So this time it is a simple black to transparent fade, making it possible remixing easily once there will be other blending modes supported as well. Probably in inkscape 0.92.

Source Lazur URH

Prismatic Rounded Squares Grid 4 No Background@2X #492
 Noise  CC 0

Prismatic Rounded Squares Grid 4 No Background

Source GDJ

Vintage pattern #1960
 Grid  CC 0

Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.

Source Firkin

Prismatic Octagonal Background #439
 Noise  CC 0

Prismatic Octagonal Background

Source GDJ

Background pattern 215 #2371
 Brown  CC 0

A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.

Source Firkin

Simple bump #172
 Dark  CC 0

A simple bump filter made upon request at irc #inkscape at freenode. Made a screen capture of the making here: https://youtu.be/TGAWYKVLxQw

Source Lazur URH

Light Brown Wallpaper With Vertical Stripes #905
 Stripes  CC BY-SA 3.0

This seamless light brown background texture resembles a wallpaper with vertical stripes. One way to use it is as a tiled background on web sites.

Source V. Hartikainen

Connected #348
 Light  CC BY-SA 3.0

White circles connecting on a light gray background.

Source Mark Collins

Decorative divider 218 #2232
 Dark  CC 0

Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.

Source Firkin

Carbon Fiber #3
 Carbon  CC BY-SA 3.0

A dark pattern made out of 3×3 circles and a 1px shadow. This works well as a carbon texture or background.

Source Atle Mo

Background pattern green #1947
 Green  CC 0

To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.

Source Firkin