A disposable, non-toxic, biodegradable, flexible cover fitting on beverage containers to protect from unwanted contamination or spillage is described. In one embodiment, the flexible cover includes a system comprising a tamper-evident package and a cover sealed within the tamper-evident package, the cover including a flexible body having a substantially flat, circular shape and a first thickness and a bead having a second thickness disposed about a circumference of the flexible body, wherein the second thickness is greater than the first thickness.