I'm curious, by your logic that plants are as sentient as animals in their own way, does that mean that if it is ok to eat animals, it is also ok to eat people?....
Ethically, do you feel it is better to eat a person who has been hit by a car than to pull a plant out of the ground?
No, I wouldn't extend it to people as, mainly for reasons given by Aurynne, cannibalism is a taboo in our society and eating other people of our own species is not biologically a good idea.
The main other reason is that people are individually loved and owned (in a family/relationship rather than slavery sense). If a bus knocks down and kills a pedestrian and you run straight over with a knife and fork and your napkin on, you will cause horrendous traumas for the person's loved ones. In the same way, I wouldn't advocate eating a pet that had been run over - not because of its species, but because it is acknowledged, owned and loved by somebody.
However, a wild animal that isn't owned by anybody (or one that is, by an untraceable person, but almost certainly as livestock rather than as a companion), I wouldn't see the problem. Purely ethically speaking, if a fox has taken a chicken and you find and eat it, you haven't killed or sanctioned the killing of anything; if you pull up crops for food, then you have. Also, the dead chicken probably won't have been sprayed with pesticides to kill off insects so as to reserve the food for YOUR own species' pleasure, unlike the crops.