Finished

I'm very pleased with my mitered afghan, not least because I struggled so with it.  I made up the pattern myself, as I mentioned earlier, and was frustrated to find that it wasn't square.  We believe this is because the double crochet stitch, at least when I use an K hook and Lion Brand homespun, is not the same length vertically and horizontally, so each row made it less square by just a minute amount (I didn't notice til I was rows and rows in.) 

Anyway, I like it, though I'm not sure I'll make another one like it.  

And I had a lot of fun photographing outside, hence all of the photos.

I think you can see the mitered pattern (think Log Cabin Quilts) and the edging here.

It's almost square.  The mitered pattern (and my stitch) means two edges are longer because the double crochet is not the same legnth vertical and horizontal.  

Not sure why the bottom is grayed out.

Another view, maybe better colors.

The 3 dc round, then sc round, then shell, then chain stitching for the edge.

That's the original Granny Square in that corner.

Giant Mitered Granny Square Afghan
I'm not great at writing patterns, esp Round 3, 4, and 5.
K hook
Lion Brand Homespun Ocean

Rnd 1: Ch 4, join with sl st to first ch made to form ring. Ch 5 (counts as 1 dc + 2 chs),

*work 3 dc in ring, ch 2, rep from *twice more, work 2 dc in ring; join with a sl st to 

3rd ch of beg ch-5. (four ch-2 corners) DO NOT TURN WORK.

Rnd 2: Ch 1, sl st into next ch-2 sp, ch 5, work 3 dc in this ch-2 sp, *ch 1

(3 dc, ch 2, 3 dc) in next ch-2 sp, rep from * twice more, work 2 dc in final ch-2 

sp (which is right beside the beg ch-5); join with sl st to 3rd ch of beg ch-5.  Ch 3.

Rnd 3:  3 dc in same space; 3 dc in the space between the 2 groups of 3 dc of the previous row; 3dc, ch2, 3dc in next ch 3 corner space; 3 dc in the space between 3 dc; dc and then ch3 in the next last space.  Turn.

Rnd 4:  3 dc in space between 2 groups of 3 dc of previous row; 3 dc in each space until corner; in corner space, 3 dc, ch 2, 3 dc; 3 dc between groups until end space between 3 dc; and then ch 3 in last space (between chain and 3 dc below).  Turn.

Rnd 5 etc:  Work Rnd 3 and 4 repeatedly as if these are rows, turning at ends with ch 3 and working 3 dc, ch 2, 3 dc at corner.  Finish off.

Edge:  Work 3 dc in every space on all four sides.  Then work sc in every space on all four sides.  Work shell (*sc, skip 2 sp, 5 dc, skip 2 sp* repeat).  Then edge with chain stitch (or whatever you want to call it--not quite a sc:  insert yarn in sp, pull through, yo, pull through both stitches)

Adapted from Crochet Again