Rose

Keep one as a souvenir and let the rest go. No recipe, tea or pie on the site asks for a rose, and the game's own text for it is a two-word joke about romance. Whether eating one does anything, the game does not say. Picked, it is a flower taking up an inventory slot.

Most of them reach you by accident. Wild roses are where rose seeds come from, so anyone after seeds for a flower bed comes home with a stack of blooms as well. Say you are walking back from a meadow with your bag nearly full and a crate shows up by the road. The roses are the first thing to drop.

If you like roses around the base, the living plant is the point. Grow it from seed, keep a clone of one that grows well, and leave the picked ones out of your boxes. What you can actually eat is listed under Food.