There aren't many grocery stores near campus that are easy for carless students to walk to. There are even less that have healthy food. Unfortunately, I didn't discover CGFC until after a year, since it seems to be a bit of a secret.
It's tucked into Springfield Avenue, in a church not too far from Green Street. They have a variety of foods ranging from local produce to tea. The produce selection is not too big, but they have great locally grown crops. Their fresh baked breads are quite delicious and seem to sell out fast.They have lots of boxed items that are great for college students who want to eat healthy, such as soy milk and organic soups. Also they have a selection of frozen natural foods, dairy products, and even some natural toiletries.
My main compliant would be with the fact that they have no meat. I know many if not most of the people shopping there are vegans or vegetarians, but it leaves people who buy free range or local humanely raised meat without any options except a loooong trip to a "big box" grocery store.
If you don't eat meat, this is the best place to stop. If you do you might have to supplement with other stores, but it is still a great place to go.
If you shop at CGFC regularly, you do have to purchase a membership, but I don't think they are terribly expensive. Considering that many products are much cheaper than what they would be elsewhere, since CGFC is non-profit, a membership should pay for itself if you shop a lot. If you are particularly cash strapped or simply want to save money, they give a discount to volunteers, who staff the store.