Like gnathaniel said,
Bletilla striata is a native of some of the southern provinces of China (maybe a few northern ones too, idk).
The reason this species is able to naturalize very easily in your area is that the seeds germinate so easily, that in cultivation, you don't even need to to send them to a lab to have them sow the seeds.
Just grab a pot and fill it with potting soil and disperse the seeds on the surface and water. That's it! They will germinate in 2 wks to 1 month! Not a whole lot of anything special needed!
It takes a long time for the protocorms to grow out into seedlings though (about 1 yr).
Bletilla striata is also very easy to grow, imo, if they grow in temperate and subtropical climates.
They go deciduous prior to dormancy.
Bright indirect sun is good.
It doesn't have to be all that humid (40% - 60% is fine).
Dormancy is around mid to late Nov. At this time they should be grown completely dry.
A well draining woodland or grassland type soil is good.
If you don't want these to compete with your true native orchids, remove the orchid while it is dormant, and grow in a pot on your porch or something. Don't allow it to set seed. Or if you want seeds, make sure the capsules are covered with something to prevent the seeds from getting loose.