Jane, I was curious about the same thing, & I found an article that says ornamental sweet potatoes are edible. You can use the link to read the same article. I heard somewhere that you can get new plants from the old but I don't recall the details. I wintered over mine in a pot in the house. Hope this article helps you.

Here is a link that might be useful: ornamental sweet potato

Yes, it's extremely easy to propagate ornamental sweet potatoes from slips off the potato, or just from cuttings taken before you dump the plant. I've never grown a sweet potato that wouldn't root in water in no time flat - right now I have Margarita, Lady Finger, and a white-fleshed sweet potato grown from the cut-off end of one we bought last year for New Years (my husband is Japanese, and we have to have Kuri Kinton for New Years, among other foods).
FWIW, both Blackie and Margarita were selections that showed up among varieties being trialed for eating, according to Allan Armitage.

And all this time I was lead to believe they weren't edible. I've been composting them all along. So has anyone actually eaten them yet? If so, did you treat them as any other potatoe? According the link above the tricolored is also edible. trudyjean

I am a Horticulturist for a large garden here in Utah! When we dug up ours---we had hundreds of pounds of them---Yup--all went to the dinner tabble! And a few are in storage for next years crops! LOL! Crops(for me)--DIsplay(for others)!!!

Ryan

These ornamental sweet potatoes are unknown here french Riviera where they should thrive.
I would like to get some little roots. Any available? I will pay sending costs and may be exchange another plant.