General

American Horticultural Society
http://ahsgardening.org/gardening-resources

Grow Native Massachusetts
https://www.grownativemass.org

Massachusetts Horticultural Society
https://masshort.org/

Massachusetts Master Gardeners
http://massmastergardeners.org/

UMass Extension
https://ag.umass.edu/

United States Department of Agriculture National Agricultural
https://www.nal.usda.gov/home-gardening 

Chicago Botanic Garden
Chicago Botanic Garden 

Plant Identification:

Go Botany- The New England Wildflower Society
https://gobotany.newenglandwild.org/

Missouri Botanical Garden (with pronunciation guide)            http://www.missouribotanicalgarden.org/plantfinder/plantfindersearch.aspx

Fine Gardening Plant Guide
https://www.finegardening.com/plant-guide

USDA Natural Resources Conservation Service
https://plants.usda.gov/java/

Poisonous Plant Guide
https://www.homeadvisor.com/r/poisonous-plant-guide/