Here's the link to the USDA Plant Database http://plants.usda.gov/java/ - where you can find information about plants, mosses, etc. that from all over the US and its territories.
The plant names include distribution, species information, characteristics, images, links to more information and references.
The site is focused on land conservation and provides information intended to provide an information exchange throughout the world.
The PLANTS site is a collaboration between USDA NRCS National Plant Data Team (NPDT), the USDA NRCS Information Technology Center (ITC), The USDA National Information Technology Center (NITC), and many other partners.
Pollinator conservation has its own link full of references to other resources.
Also, click over to the Fact Sheets & Plant Guide at http://plants.usda.gov/java/factSheet
There is a lot to explore and discover!