Graphy@2X #351
 Grid  CC BY-SA 3.0

Looks like a technical drawing board: small squares forming a nice grid.

Source We Are Pixel8

 More Textures
Colorful Floral Pattern Background 8 #230
 Fabric  CC 0

PDP

Source GDJ

Cardboard #278
 Paper  CC BY-SA 3.0

A good starting point for a cardboard pattern. This would work well in a variety of colors.

Source Atle Mo

Background pattern 254 #2144
 Dark  CC 0

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

Source Firkin

Prismatic Geometric Tessellation Pattern No Background #551
 Noise  CC 0

Prismatic Geometric Tessellation Pattern No Background

Source GDJ