Try double-clicking on the pod that Mr. Poppy Head (peanut with the hat) is in.
I had the same issue. I can't manage this last clue. please help me out!
You'll want to click your mouse twice (don't wait too long between clicks or it won't work) on the pod that Mr. Poppy Head is in...
not the pod you're in. The first click will open the pod and let out Mr. Poppy Head, and the second click will move you (Mr. Lantern) into that pod.
Then do the same thing with the pod that has the creature with the face.
Once you're in that pod that the creature with the face was in, the last thing you'll do is click once on the pod that Mrs. Mushroom is in (it will leave the pod it's in), and then quickly move your cursor and click once on the pod with the glowing seed in it.