How do I stop this annoying cat from whining?

When you saw the cat eating grass there was nothing wrong with it, cats eats grass when they are not feeling good its like us when we eat to much we find something that helps us to relieve it. Grass helps a cat get rid of what ever it is that makes them feel bad. The cat may have not look neglected because cats do find food resources even if its from a trash can which could be the reason it was eating grass. When you feed the cat and continued to do so you made a friend, the cat now knows that she/he is getting better food someplace else and will continue to keep coming back. The cat has established your place as a place to go for food. Cats are very funny, I had four of them all different and unique in their own way I have a cat right now that gets food and water she is an indoor cat and she is fixed but she cries to my husband all the time, I take it that she is telling on me for something. The thing about a cat is that they will stop doing something when they want to, not when you want it to stop. the cat could of been an indoor cat at one time and got out and that is what the cat may be used to and the cat might be simply seeking attention. If you think there is something wrong with him/her then maybe you ought to call a no kill shelter and let them know what happened and some of these paces take cats in, you can also try taking a picture and posting it up, someone may of lost him/her, but if you are real concerned and don't want to deal with it call a no kill shelter. One thing I learned from any animals is that when you feed them they begin to depend on that source. I hope that helps