First let me say how very sorry I am to hear about your family's loss. That must be incredibly difficult for all of you.
Regarding the flowers, there is not a way to root cut flowers and have a good chance of them actually making it. Perhaps the best option would be to consider drying them if you would like to preserve them. Most of the ones you listed can be dried by various means, with iris being an exception. It might also be a good idea for you to purchase some of these same plants and plant them in your garden to serve as a memorial.
Thanks for the question. Please stop in to the Home Depot website again soon if I can help with any follow up questions on drying flowers.
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