I think there were four Griswold kettles with pit bottoms made; Eccentric Kettle, Eccentric Bulged Pot and Extra Large Eccentric Pot (Style B). These are shown in the c.1930 Griswold catalog. Additionally a Low Eccentric Kettle was made earlier but discontinued. All of these are rare to a degree but not especially valuable since there is not much demand for them.
A trivet was made for them (or some of them) and is unmarked. It looks like a floor drain grate sort of.
Steve