What is this tomato?

It came from seeds someone gave us last year. It's green inside too. Very sweet tomato taste.

Another one

Looks like it might be a green zebra. Check out the plantfiles link:

http://davesgarden.com/guides/pf/go/53465/

Looks similar but these are small. About the size of a large walnut. I wonder if some of them just grow smaller?

My green zebras are not too large. Larger than yours, but you describe the taste accurately.

Green Zebra it is! Thanks myrrh & girlgroupgirl!