In the future they will mainly serve as decoration. Putting them in a vase for example, as you already expected. Eventually they will also be used to get different dyes, and for alchemy stuff ofc.
We always wanted to add different varieties, already made some preparations. I hope we get them ready for the next big update.
And about your last question: Yes, soon they can be replanted, as well as trees/saplings and all other plants/corns ![]()