Background pattern 235 #2255
 Yellow  CC 0

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

Source Firkin

 More Textures
Prismatic 3D Isometric Tessellation Pattern 6 #148
 Dark  CC 0

Prismatic 3D Isometric Tessellation Pattern 6

Source GDJ

Background pattern 261 #2076
 Dark  CC 0

Inspired by a pattern found in 'A General History of Hampshire, or the County of Southampton, including the Isle of Wight', Bernard Woodwood, 1861

Source Firkin

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

Retro Squares Background 6 #396
 Noise  CC 0

Retro Squares Background 6

Source GDJ

Colorful Floral Background No Black #481
 Light  CC 0

Colorful Floral Background No Black

Source GDJ

Vintage pattern #1959
 Grid  CC 0

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

Source Firkin