I soaked them for about 15 hours, and I just saw a recipe on Marmiton that says to soak them for 24 hours. I've never considered soaking dried beans for such a long time. But even after all that soaking — trempage in French — these little white beans still weren't completely cooked in the crock pot after five hours. I cooked a whole kilogram of them — that's 2.2 lbs.
They're called « haricots cocos » or « haricots cocos blancs » — I'm not sure about putting a S on blancs or on coco. The French language is very complicated when it comes to these agreement things, and sometimes trying to figure out how it works seems like a waste of time. Better just to eat the beans, which to me seem to be what we call "navy beans" in the U.S. They are smaller than "great northern" beans and much smaller than French lingots, aka cannellini or white kidney beans. This site says that navy beans are also called "Boston beans, the white coco, pea beans or alubias chicas."
My navy beans finally cooked on low heat in the crock pot for 10 hours or so, even after the long soak, and they are really good. We had them with some collard greens. I didn't bother making Boston baked beans with the coco(s)... yet. We just ate them as they were, with lardons fumés and sausages, yesterday. I bought three types of sausage, as you can see in the photos: saucisses de Strasbourg (weenies, basically), saucisses de Montbéliard (smoked pork sausages), and a saucisson fumé cuit à l'ail (a big fat garlicky smoked sausage). I think that tomorrow I'll make Boston baked beans with the leftovers.