I know some brewers use different things to add bitter flavours or enhance the aroma ie elderflower, peach etc but I was at my grandparents house today (well, Mim's g/parents

) and her nana wants rid of a lemon balm plant. It is a member of the same family as mint and I was wondering whether I could use it in a brew?
Having researched it, I've noticed they contain tannins but so do hops and I was wondering whether I could use some for either bittering or aroma?