This light yellow background pattern consists of an irregular pattern of spots. Here's a light background pattern with yellowish tint.
Source V. Hartikainen
One more brick pattern. A bit more depth to this one.
Source Benjamin Ward
Remixed from a drawing in 'Jezebel's Daughter', Wilkie Collins 1880
Source Firkin
A seamless light gray paper texture with horizontal double lines.
Source V. Hartikainen
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
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Embossed lines and squares with subtle highlights.
Source Alex Parker
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
Prismatic Curved Diamond Pattern 5 No Background
Source GDJ
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
A topographic map like this has actually been requested a few times, so here you go!
Source Sam Feyaerts
Black & white version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Pixel by pixel, sharp and clean. Very light pattern with clear lines.
Source M.Ashok
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
A heavy hitter at 400x400px, but lovely still.
Source Breezi
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
Detailed but still subtle and quite original. Lovely gray shades.
Source Kim Ruddock
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A slightly grainy paper pattern with small horizontal and vertical strokes.
Source Atle Mo
The image depicts polka dot seamless pattern.
Source Yamachem