geese not eating help

I have two 4 month old white embdens. They are spoiled like all our animals. Ever since they were little  (4weeks old) I have had to supplement their feed with greens as there isn't much in their yard. They have always eaten a green salad three times a day made up of collards,romaine,spinach,frozen peas and frozen corn. This is in addition to their feed which is free choice. All of a sudden they are not eating anything but the frozen peas and corn. I have tried fruits to no avail I have cut grass for them and still they won't eat it. I'm getting worried that they will not get enough vitamins from just the feed. Does anybody have any suggestions as to something that I could try. Its getting expensive buying frozen vegtables  all the time. Also I am floating their food so I know that isn't the problem. thanks Micki

Thanks guys But I have pools and big bowls in their yard. They have four large tubs and a large kiddie pool to swim in. I tried watermelon  cut up and they turned their noses up. Good thing the chickens loved it.  I have cut grass and put it in water and they still don't want it. I know the frozen veggies are cold but so are the other greens I give them. When I make their salad it comes from the fridge and I put cold water in their bowls to float it. I am at a loss as to what to try next. I have a list of things that are harmful to chickens but I know waterfowl is a different story. Anybody got a list for waterfowl I could try. Thanks Micki