Buckley’s yucca, or Yucca constricta, is a native plant in the agave family. It can grow up to 10 feet tall. They like high sunlight levels and do well in drought conditions. They produce white flowers in late spring and early summer. If they can reach them, deer like to munch on the flower spike. It is commonly used as an ornamental because it attracts butterflies and is a hardy plant. I found these plants at Inks Lake State Park a couple of weeks ago.
My iNaturalist observation can be found here.
Source:http://www.wildflower.org/plants/result.php?id_plant=YUCO