I would love to ask a few questions but since I can't, I will answer based on the pictures. 

First the best way to tell if you have a plant from the mint family is by examining the stem. Plants in the mint family have square stems. The plant you have looks like a mint to me. If it is a mint, they are edible. They can be used in teas and cooking.

It looks like lemon balm. The mild lemon scent is consistent with it being lemon balm. The plant can take over a garden bed. It spreads by seed mostly so do not let it go to seed. Unlike other mints it does not spread by underground rhizomes. This means it can be dug out or pulled easily but you will have to get and keep ahead of it.

If you want to have it for culinary uses, I recommend growing it in a pot. This is true of all the mints. 

If you have further questions, you can contact your local Extension professional. Your contact information says you are in Cuyahoga County. I have included the contact information for that office. The emails are for the Master Gardener Coordinator and the Natural Resources Educator.

Enjoy your lemon balm.

Cuyahoga County Extension

12200 Fairhill Road, E. Building
Cleveland, OH 44120
Phone:<personal data hidden> <personal data hidden>   <personal data hidden>