Several folks have mentioned that they occasionally see a spot of blood in an egg. Now I just assumed that this was because our hens run with roosters, but I've done a little research and this is not the case. Here are the main points I found.
Eggs with a visible blood spot occur in less than 1% of all eggs laid, and are safe for consumption. The spot is caused by the rupture of a blood vessel during the formation of the egg, and can be removed with the tip of a knife. In industrial situations, all eggs are candled and those with spots culled. Interestingly, blood spots are more likely to occur with hens laying brown eggs. Not only does the color of the shell make candling more difficult, the genetics of these birds predisposes them to lay eggs containing spots.
Each yolk begins within the hen's ovary, and is enclosed in a sack containing blood vessels facilitating its development. Normally, when the yolk is mature it is released from the "stigma" or "suture" line, which is the only area of the yolk sack free of blood vessels. When on occasion the yolk ruptures at another point, the small blood vessels supplying the yolk with nutrients rupture, thus causing a spot of blood to appear on the yolk or in the white.
Importantly, this spot fades over time, and so a bright blood spot indicates a very fresh egg! This is because, as an egg ages the yolk takes water from the albumen and dilutes the color of the spot, making it unnoticeable. Once I learned this I realized that the people reporting such spots were, in fact, receiving eggs laid that same day.
Eggs that you buy in the store are, on average, two weeks old before they reach the grocer's shelf, let alone your fridge and belly. Until now there have been times when I am a few eggs short on a given day's order, and will go out to the nesting coop to get a few. These are the eggs that, more than likely, contain the spots. Since learning this, I've begun to let eggs sit for a day or two before distribution. (Just FYI: Ecotone eggs are always less than a week old; in fact, we sell all the eggs we have every two or three days.)
So, in short, these spots indicate an extraordinarily fresh egg and, aside from aesthetics, are completely safe to consume and enjoy!