Lined Paper@2X #363
 Stripes  CC BY-SA 3.0

The classic notebook paper with horizontal stripes.

Source Are Sundnes

 More Textures
Vintage Elegant Floral Background #257
 Fabric  CC 0

PDP

Source GDJ

Noisy #45
 Paper  CC BY-SA 3.0

Looks a bit like concrete with subtle specks spread around the pattern.

Source Mladjan Antic

Prismatic Snowflakes Pattern 3 No Background #413
 Light  CC 0

Prismatic Snowflakes Pattern 3 No Background

Source GDJ

seigaiha subtle color #2278
 Pink  CC 0

This is a remix of "blue wave-seigaiha".I hope this subtle color version of Seigaiha would be suitable for background .

Source Yamachem

Prismatic Groovy Concentric Background #449
 Noise  CC 0

Prismatic Groovy Concentric Background

Source GDJ

Background pattern 306 (colour 6) #1878
 Colorful  CC 0

Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.

Source Firkin

Background pattern 256 (colour) #2138
 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

Squares@2X #303
 Dark  CC BY-SA 3.0

Dark, square, clean and tidy. What more can you ask for?

Source Jaromír Kavan

Colourful background #2009
 Colorful  CC 0

Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic

Source Firkin

Background pattern pink #1954
 Pink  CC 0

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

Source Firkin

Joined spirals pattern #2482
 Yellow  CC 0

The starting point for this was drawn on the web site steamcoded.org/PolyskelionMaker.svg

Source Firkin

Concrete Wall #77
 Wall  CC BY-SA 3.0

Dark blue concrete wall with some small dust spots.

Source Atle Mo