There are so many kinds of beans that it is really difficult to do this based on so little. Here is a link to the Seed Savers Exchange, online seen catalog (beans section). There's a chance you might see them there, or something like it.

Some years ago a Gardenweb member posted a similar question about a family heirloom bean from his family. It had brown seed. He wondered if it might not be the same as our family heirloom bean: Tennessee Cutshort. Eventually he sent me some seed. I thought, "This is like looking for a pin in a haystack!" But, when the seed arrived it looked just like Tennessee Cutshort. When I grew it out it seemed the same in every way! So, it is possible, sometimes, to find an ID.

George
Tahlequah, OK

Here is a link that might be useful: SSE bean catalog listing