As a Catholic I can tell you that the matter we use for the Eucharist are unleavened bread and wine.
Some non-Catholic communities use grape juice and crackers because they have prohibitions on alcohol and because they do not believe that Jesus actually meant what He said in John 6, that we must "eat His flesh and drink His blood" to have eternal life. Hat it is "real food and real drink."
Where these groups see symbolism the Cahokic Church follows the Words of Christ and offer that which He did in priesthood of Melkizedek, which was bread and wine. This is the non bloody re-presentation of the eternal sacrifice on Calvary.