I find Chamomile capsules to be very good for that sort of thing. Its a non-Pharmaceutical herb and won't leave you feeling stoned.
You can buy it at any grocery store in teabag form, but you have to make it very strong as tea, like 4 teabags per 1 cup of tea and it's got a bit of a grassy flavor.
If you order it online in capsules, you can just take a couple with a glass of water. I've used it in situations where I had to deal with a fairly high volume of walk-in customers and helped keep my nerves from getting all jangly and keyed up. Good for several hours.
The Mental Health counselor who recommended it to me said it was equivalent to taking a couple of Xanax. I've never had Xanax, so I can't say, but the Chamomile works for me and I've recommended it to one friend who tends to have strong reactions to things like sedatives and it seemed to help them, too.