It's illegal to ship alcohol via the US Postal Service (although I think I recall reading that might change, but as far as I know it's still illegal). It is NOT illegal to ship via FedEx or UPS, but it's technically against their policies if you're not a licensed distributor (at least as of my last knowledge). That said, I've shipped via UPS without issue. Just wrap them in ziplock bags just in case, then bubble wrap the hell out of them. If you're not worried about a bottle bomb while at home, I doubt it'll be an issue while shipping, but whoever's recieving will probably want to give them time to settle. I've always filled out the online form and printed my own shipping label and never been asked the contents. But I know others have used "live yeast samples in glassware" or "collectible glassware" if asked and they've been fine (probably depends on who you're talking to).
Souring: '14 Brett C Old Ale, '15 Lambic, '14 Lambic, '14 Flemish Red, '15 Flemish Pale, '15 Oud Bruin, '15 Session Kriek
Cellar: '10 Brett B Tripel, '11 Lambic, '13 Brett C English Barleywine, '13 Quadrupel, '13 Sour Stout, '14 Brett C Bitter, '14 Spontaneously Fermented Cider, '15 Wee Heavy, '15 100% Brett B Red, '15 100% Brett L Kriek, '15 Bière de Garde