Ruby, it is doubtful that plants feel in the same manner as humans. It is true that they do not have a nervous system. However, they do respond to experienced stimuli. These responses are call tropisms.
However, you seem to be asking a philosophical question. And I'll try to answer it in that vein.
The force of nature that makes a plant grow is possibly the same force of nature that makes us do the same. Call it God, Mother Nature, The Force, whatever. Therefore if you feel it's bad to eat a living creature, then you might need to acknowledge that plants are alive - no doubt about that.
Now, you narrow your argument and define what's good and bad to eat, out of the list of living organisms. You make a case for using the nervous system as your cut-off point. That's somewhat avoiding the debate in one way, but is it any less moral for me to set my theoretical 'line in the sand' at a higher level, and say, ok, I acknowledge I eat once-living entities to survive, but my cut off point is that I will only eat those organisms that my body and culture decide are acceptable? If I dislike the idea of eating horse, i will choose not to, but i will not starve rather than try it. Similarly, eating cabbage isn't on my to-do list anytime soon, but i won't discount the idea.