Vomiting undigested food is called regurgitation. Common causes for regurgitation are intestinal parasites, esophageal disorders (megaesophagus, strictures, inflammation), etc. This is what you can do:
1- Raise the feeding
bowl to a small stool to force her to eat slower.
2- Consider feeding smaller amounts more frequent. In other words, divide her meals to 4-6 times a day.
3- Consider getting her dewormed. You can buy Fenbendazole (panacur) and give it once a day at label dose for 3 days. Repeat after 3 weeks.
4- Dogs are not strict carnivores, eating plants can be a sign of a lack of fiber in their diet. Consider adding baby carrots, broccoli and cauliflower to her diet.
5- Eating stool is a sign of boredom, hiding evidence, bad behavior
, etc. There is a product called "Forbid." Add it to her food and will not change the taste of the food but it will change the taste of the feces hopefully to stop her from eating it when she does.
6- If after doing the above there is no improvement, consider having her checked by your family veterinarian.
Hope the above helps, if you have additional questions I will be glad to answer them.