US sim card for free

Someone on this site very kindly gave me a AT & T sim card with $15 credit on it a few months ago. I've since been to and from the states a couple of times topped it up and have come home with $10 credit which will expire in about 21 days time. If anyone is visiting the US and would like to use up the remaining credit please send me a PM and we can arrange a handover. The sim is only good for the continental US calls and messaging and will not work for overseas calls or in Canada.

Helen