This poster was made just three weeks ago by a Woodside, California resident who’s dog died recently from eating poisonous mushrooms on their front lawn

the poster was added to this doggy board

http://www.boxerworld.com/forums/dog-health-issues-questions/153219-mushroom-warning.html

the URL in the poster refers to the North American Mycological Society which produces their own warning posters

http://www.namyco.org/toxicology/index.html

this warning poster is also available at the San Francisco Mycological Society

http://www.mykoweb.com/misc/warning.html