I have been playing around making home made bread using beer and spent grain. Still a work in progress because I love to tinker with any cooking/baking recipe to 'make it better'
Been turning out some nice bread to go along with my home made beer. It doesn't take much grain (depending on how grainy you like your bread), usually a cup or a cup and a half per loaf. So obviously whether using steeping grains or mashing grains you are going to have way more than you need for a loaf or two. No need to throw the rest out especially if your beer brewing is infrequent or sporadic. You may have occasion to need more before the next scheduled brew day. I have found that you can freeze the grain in ziplocks quite nicely. My preferred method is to put a cup and a half of grain into fold style sandwich baggies securing the opening by folding and then rolling the loose section of the baggie over the used portion. I take several of these and put them in a Gallon size ziplock, squeeze out the air and put in the freezer. When needed it is an easy task to pull out a single package and reseal the rest. I find no need to dry the grains before freezing. I just freeze them after they self drain in a strainer a bit. When I unthaw the packages I usually spread them out on a dinner plate letting them dry out over night. I have also dried them out in the microwave. You can use them wet although depending on the amount of water present in the grain you may want to reduce/adjust the water used in the bread recipe. I have done this in both a bread machine and also baked in the oven. Both work out great.
A nice home brew and a couple slices of beer grain bread.......Mmmmm