This is milkweed. It looks to me to be Common Milkweed. Lucky you if this is on your property! It is a valuable native plant, especially for the Monarch butterfly. The botanical name is Asclepias and there are many varieties or cultivars that have emerged. 

Here is some information about Milkweed from the Delaware Nature Society: https://www.delawarenaturesociety.org/blog/magical-milkweeds-the-plants-that-check-all-the-boxes/

And from our Extension colleagues at Penn State: https://extension.psu.edu/monarchs-and-milkweed