safety valve: a valve in a container in which pressure can build up (as a steam boiler); it opens automatically when the pressure reaches a dangerous level
regulator: any of various controls or devices for regulating or controlling fluid flow, pressure, temperature, etc.
pholiota flavida: a fungus that grows in clusters on the ground; cap is brownish orange with a surface that is smooth and slightly sticky; whitish gills and a cylindrical brown stalk