@Marilyn
There are definitely plants that are toxic to dogs if eaten. A little grass doesn't hurt them- they don't eat a lot. It is weedy grass. I have made sure to identify the weeds in the fenced area of the back yard that they have acces to and made sure nothing is toxic. Not all my dogs do this and the ones that do don't do it all the time. I also never have them outside unless my husband or I is out with them to supervise. They are indoor dogs, only out for potty and for periods of play in nice weather.
