Robby, Dulse, aka duilsk, is a type of edible seaweed. It tastes quite salty & somewhat fishy. An acquired taste, it used to be chewed by the older folks, a bit like chewing tobacco or chewing gum.
I haven't seen yellow-man myself but I was told it is a kind of fudge or toffee, usually served in sticks, like a stick of rock.
Thanks Yvonne (Quincy) for posting the lyrics. My mother used to sing this sometimes, but only knew the first verse. By the third repetition, I be goin' nuts.