Do they look healthy? Do they have nice red combs? I'll bet you have hidden nests all over the place. Hens have no idea they're "supposed" to lay in a box. They like to lay under bushes, behind trash cans, in open sacks of dog food, etc. Probably not under the shed if it's where everyone hangs. Hens want privacy and quiet for their nests. Try confining them to a coop or run for a few days and I'll bet you'll be blessed with eggs.
