Checkered Light Emboss #280
 Grid  CC BY-SA 3.0

Sort of like the Photoshop transparent background, but better!

Source Alex Parker

 More Textures
Sakura Blossoms Background #389
 Noise  CC 0

Sakura Blossoms Background

Source GDJ

Fabric pattern 3 (colour 6) #2382
 Fabric  CC 0

Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.

Source Firkin

Iron Grip #587
 Dark  CC BY-SA 3.0

Sounds like something from World of Warcraft. Has to be good.

Source Tony Kinard

Background pattern 215 (colour 2) #2370
 Blue  CC 0

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

Source Firkin

Background pattern 235 (colour 3) #2253
 Pink  CC 0

To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.

Source Firkin

Retro Squares Background 5 #395
 Dark  CC 0

Retro Squares Background 5

Source GDJ

Background pattern 221 #2347
 Dark  CC 0

A seamless pattern formed from a tile made from ornament 22. To get the tile, select the rectangle in Inkscape and use shift+alt+i.

Source Firkin

Real Carbon Fiber@2X #287
 Carbon  CC BY-SA 3.0

Carbon fiber is never out of fashion, so here is one more style for you.

Source Alfred Lee

Floral pattern 15 #1753
 Dark  CC 0

The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i

Source Firkin

Colorful Floral Background No Black@2X #482
 Light  CC 0

Colorful Floral Background No Black

Source GDJ

Prismatic Abstract Geometric Background 4 #271
 Noise  CC 0

Prismatic Abstract Geometric Background 4

Source GDJ

Japanese family crest called chidori #2443
 Fabric  CC 0

The image depicts a seamless pattern of a Japanese family crest called "chidori" in Japanese .A chidori in Japanese means a plover in English.

Source Yamachem

Starting Diamond Shape #137
 Light  CC BY-SA 3.0

Simple blue and line to mix.

Source SliverKnight

Retro Squares Background@2X #415
 Noise  CC 0

Retro Squares Background

Source GDJ

Background pattern 105@2X #564
 Dark  CC 0

A seamless pattern formed from background pattern 102

Source Firkin

Background pattern 29 #200
 Dark  CC 0

Pattern produced in Paint.net using the Vibrato plug-in.

Source Firkin