There may not be a true silver crown of an independent Ireland. The closest that I have uncovered would be the silver crown, presumably issued by the Catholic Confederacy of Kilkenny, in 1642-43, although the few examples that appear in auction sales appear to be less than 25g in weight. These coins are also quite rare. The next closest example of an Irish silver crown, which I was able to acquire, might just be the "Ormond" crown of the same time (1643-1644), issued by the Earl of Ormond, James Butler, commander of the royalist army in Ireland. At least it is a silver crown sized coin (my example is 29.71g), most likely minted in Dublin, and during the time when there was an independent government that controlled two-thirds of the island. This brief period of independence would end in 1653 with the occupation and annexation of Ireland by the Commonwealth of England.
Obverse design, crowned CR for King Charles I. Reverse V with a small S above for denomination of 5 shillings.