My botanist friends and I were hiking in Anchor Diamond Preserve, near Ballston Spa, New York. There we found Summer Snowflake blooming deep in the woods, far away from any cultivated garden.
Their website http://www.capitalmohawkprism.org/ has more information if you wish to pursue
this issue. Anyone finding Leucojum growing in the woods or along a stream should report the location
to this organization.