Ok it was 3crates of glowi. From your rolls you know that; Glowi grows in the underdark and is used primarily for there glowing properties bunch enough up and you have a nice enough light. When ground down they form a glowing paste useful for making marks on walls. They are also mildly poisonous and when treated just right become fatally toxic.
You remember Gheedon saying earlier there where only 100 glowi in a crate and that they are sold by weight. People looking to buy would be people working in dark places for extended periods(miners etc) where running torches could be costly, adventurers also for the marking paste. Given that it can be made into a deadly poison you would assume there is some sort of black market for it.