They are food; you can sell them, or click on them to sleep and eat them.
For me, after the beginning of the game food in general became just extra weight. I didn't use much mana, so the healing spell (in general) or potions (during fights) were enough that I never bothered to sleep. I started sticking most of the food I gathered in a barrel kept in the BF, in case I started running low on potions, or otherwise needed to resume sleeping in the game.
There are also a couple quest related roots, which have unique names.
