I would suggest foam, like from an eggcrate mattress, to pack them in, if you send the actual fruit. I used it in an egg drop contest in school (many many years ago- we had to use something lightweight that wouldn't let the egg break when we dropped it off the pressbox at the football field
), and it worked like a charm! I'd wrap each one in something like a cotton sock or piece of fabric, to protect the skin. And if she finds she likes the taste of them, she can save the seeds from one and do it again next year!
But if you just want to get her heirloom tomatoes, in any way, shape or form, I'd go with the seeds
(just planted my starter plants in the big pots this weekend
- of course, I'm in Alabama, though!