Archaeological remains from the Toyah Phase (1300-1650 CE), prior to Spanish colonization of the American Southern Plains in central and south Texas, suggest that foraging indigenous peoples maintained a feasting economy. Mind-altering beverages, such as caffeinated or alcoholic drinks, are a common attraction of feasts worldwide and throughout human history. Fifty-four sherds of Leon Plain ware from six archaeological sites were chemically analyzed using ultra high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Six samples contained biomarkers suggestive of caffeinated beverage(s)—either black drink, Yaupon Holly (Ilex vomitoria) ceremonial tea, or chocolate, derived from cacao (Theobroma cacao or bicolor). Three of those six samples had duplicate results over three trials. Six different samples contained succinic and tartaric acid, sometimes associated with grape wine, but no samples maintained those results over two trials. These results suggest that Leon Plain may have sometimes been used to contain mind-altering substances, such as black drink.