I have no problems, and honestly didn't consider this, so thank you for posting!
I personally don't have any issues!
I would ask the individual directly beforehand OOC, or at the very least, wrap the dried plant separately in another (smaller) envelope or folded up waxed paper?
The separate wrapping is what I'm planning to do with enclosed spices- fabric or paper, well-folded, sealed with wax. It should also (I hope) protect the enclosed from being obliterated by the post.
Because a great deal of the player base doesn't use the forums actively or at all, I suspect the best course would be to individually ask anyone you intend to send floral bits to whether they have any allergies before sending.
good question tho b.c. some people have Serious allergies! I had an aquaintance once who was Deathly allergic to lavendar