Short answer: yes BUT......Cornstalks are pretty low nutrition, and high lignin makes it a little harder to digest. They may not like eating them but you certainly try. (of course if you didn't want them to eat it they'd love it!) Just remember the rams need to keep their energy up to take care of the girls. Some neglect to eat when there's ewes and competition around. The ladies also need to maintain a relatively good level of nutrition so they don't miscarry/absorb the pregnancy because their body decides there isn't enough food available to support new babies. If nothing else they can trample down the stalks and help break it down into compost. So don't cut their grass hay by too much and closely monitor how much they are eating. Then you MUST let us know how its working out.
Yup, they will eat the leaves and the top most parts of the stalk that they can chew off, as well as any left over corn but leave the cob. Supplement with the grass hay and pasture. mind the nutrition values of all feed stuffs.