More Textures
Transparent Square Tiles@2X #299
 Grid  CC BY-SA 3.0

The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.

Source Nathan Spady

Background pattern 104 #561
 Dark  CC 0

Background pattern 104

Source Firkin

Green Fibers@2X #92
 Dark  CC BY-SA 3.0

The green fibers pattern will work very well in grayscale as well.

Source Matteo Di Capua

Prismatic Triangular Seamless Pattern III With Background #273
 Dark  CC 0

Prismatic Triangular Seamless Pattern III With Background

Source GDJ

Interlocking pattern 3 (colour 2) #2405
 Grid  CC 0

A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.

Source Firkin

Tessellation 9 #2548
 Grid  CC 0

A seamless tessellation pattern. To get the tile this is formed from, select the pattern in Inkscape and use shift+alt+i.

Source Firkin

Colorful Floral Pattern Background 8 #230
 Fabric  CC 0

PDP

Source GDJ

Floral pattern 7 #2291
 Pink  CC 0

Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.

Source Firkin

Background pattern 226 (colour 4) #2319
 Green  CC 0

A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.

Source Firkin

Background pattern 221 (colour) #2346
 Yellow  CC 0

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

Source Firkin