This is simple seamless image creator using G'MIC and a small image of your choice. The end result can then be saved as a pattern, if you choose.

1) Open your source image. A small image with a transparent background works well. I chose gimp-logo.png from Gimp's Images folder.
~~~ I included it here to save you the trouble of looking for it. ~~~

2) In G'MIC filter, select "Faded Array" and use the default values and click 'OK'.

3) The pattern is pretty much done already but before saving it, I suggest testing it.
4) Edit > Copy Visible
5) Since the original image was 128x128, I recommend creating a new image 1280x1280. (Fit's evenly)
6) Create a new transparent layer.
7) Go to your patterns palette and drag your upper left pattern onto your new image. (This is the reason for step 4)

If all went well you should now have a transparent layer full of Wilbers, that are staggered. (Don't delete it yet!)

8) Go back to your pattern image and save as MyPattern.pat (or something similar) in your pattern folder
(C:\Program Files\GIMP-2.6\share\gimp\2.0\patterns on my machine)
and when it asks, give the pattern a name that will show in the palette, "Wilber 128" on mine.
9) Hit the refresh button on the bottom of palette, to see that your pattern is there.

Now since you created this 1280x1280 test image, it would be a shame to waste it, so lets see what you can come up with from it??
Here is mine:

You know how much I like sphere's PM. lol

G'MIC's an amazing plugin. I don't join forums lightly and G'MIC's the only group that I belong to on Flickr. So powerful that it should be integrated into GIMP itself, but, alas, the powers that be don't see it this way. Still, if you are ever want a serious (and still fun) plugin, get G'MIC. It has so much to offer that I won't insult it with listing the features that it has (since I will 100% likely miss many). I will say, if you want to put GIMP on steroids, then download it. Can't beat the price either.

G'MIC and Mathmap are the two I use religiously. I used G'MIC to create my pattern and mathmap and my new pattern to create the sphere and this new one.

Yes; I use Mathmap quite often too. Both definitely adds a feather to GIMP's cap for sure. Like your result too by the way PM.

you found a fantastic use from your pattern PhotoMaster

Those are great, Greg. That last one is stupendous.

My effort looks pretty mundane after yours. I used my googly-eyed Tux who reminds me of Columbo.

the red background really highlights the ball shape. Nice.

Hey 'O'! I love your googly-eyed tux!! I need to add him to mine!!

And I agree about the red highlights!

"Here I come to save the day!!"

A memory from my childhood was Mighty Mouse!

I remember Mighty Mouse. Very much fun!

That's cool, Greg!!! Love it!

I used the layers of this pengy smiley to make a tight formation. The array made him too tiny to see well so I just left it as it was and used it as a pattern.

Love it!! Penguines are awesome!! I love the image!