blue/green annual for full sun

I'm planning next summer's garden and need some blue/green color for full sun. I need to fill an area about 1 sq yard, all I can think of is cabbage, I guess if I planted a bunch of plants close together, they wouldn't form huge heads because they wouldn't have room. Any other ideas? Ideally a foot tall or less

Try searching for loose leaf cabbage.

This link
http://davesgarden.com/community/forums/fp.php?pid=6573674
shows collard greens which look bluish green on my monitor. I have never grown them so I don't know from first hand experience.

Cerinthe major purpurescens is blue green, and quite unusual. Here in Seattle it likes full sun, and especially the edge of a wall as it likes to flop over and dangle a bit. Here it also seeds into the wall in a mild winter. Seeds sprout easily and it grows quickly. It grows about 1 1/2 foot tall for me. Sometimes I see plants for sale at local nurseries, but not reliably. I have never direct sowed seeds, but since I get volunteers I bet they would do fine.

California poppies not blue-green enough? I guess they're closer to silver-gray.

I have grown the Cerinthe from seed, It is very easy and it transplanted well. I would think for your zone you could direct seed it easily. I do over plant it a bit as it can get leggy but if you pinch it back or over seed a bit it is fine. It does make a lovely Blue Green color.
Alberta Ann

Common Rue (Ruta graveolens) has bluish green foliage and a yellow bloom. There may be other varieties as well. Read up on it before you plant it though...some people find it invasive and the herbal scent undesirable. I used it once as an annual for similar purposes as yours and kept it about 16" tall. I didn't let it bloom, just used it for the foliage color with purple Alternanthera.

thanks for your suggestions everyone, and I'll take more if there are any others

Columbines ???

Columbines tend to get leaf miner here by June. The tall meadow-rues, like Thalictrum aquilegifolium, have similar foliage (as the species name implies) and keep their foliage pristine until fall.

Larkspur, short annual delphiniums, lobelia, viola, pansy (green envy is one), ageratum are some things that have blue flowers. There are some annual salvias that are blue as well.