I don't know if Mods cause this or not, but I'd like to believe it isn't mods at all. But basically, pressing "ALT" (or CTRL, can't remember which one) on a non-cooked Mandrake (item) will act as if you ate it, you won't gain stats but you'll be put to sleep and hear the mandrake scream.
As to the cooked mandrakes, after doing the glitch above, they appear in I think a specific coords in the world. They'll always be cooked, and if you spam the button enough, you could just spawn infinite mandrakes. Though, at the penalty of sleeping for a long time. You can even obtain them if they spawn out of the world by using the Lureplant out of bounds glitch, and then a Lazy Explorer to get back in the world.
This may or may not work with other meats. I examined a Rabbit to see what I'd say, and the rabbit screamed, so I'd assume that a cooked morsel spawned at the same location the mandrakes would. I did have a video, but it corrupted for some reason, and I don't remember the location of where they would spawn, and didn't think about taking a screenshot.