Scenting branches and leaves that are detached from the ground: 
It is permitted to move scented branches and leaves [which have become detached from the ground before Shabbos]. One may even rub the branches and pluck off leaves [with his hands] in order to increase its scent. [It is however forbidden to cut off pieces from the branch or leaf using a knife or other utensil.]
It is forbidden to smell edible ground produce that is attached to the ground, such as an Esrog. It is permitted to smell inedible ground produce even if it is still attached to the ground, such as a myrtle branch. [However there are opinions which rule the contrary, that edible foods such as an Esrog may be smelled while in-edibles such as myrtle may not be smelled. Practically some Poskim rule one is to be stringent like both opinions and not smell any produce while still attached to the ground.]
May one smell scented leaves of a pod plant?
Yes. [However according to those opinions mentioned above which are stringent against smelling all ground attached produce, then the ruling would be as follows: If the pod is on a surface of stone, metal, or glass, one may smell it. If it is on a surface of wood then it may only be smelled if the pod does not contain breathing holes. If the pod is sitting on earth it is not to be smelled unless it does not contain holes and is made of metal or glass.]
 Michaber 323/5
 They are not Muktzah as one has not removed his mind from them. [M”B 322/15]
 As the area of the which is plucked off gives off a greater scent. [M”B 322/17]
 M”B 322/17; As if this were to be allowed one may come to do so to make a use out of the cut item, such as to use as a toothpick, and transgress the prohibition of Tikkun Keli. [ibid in name of Rashal. However the Taz [322/3] rules one may cut it with a knife in order to smell.]
 Ran in name of Geonim, brought in Iglei Tal “Kotzer” 34
 Iglei Tal ibid; Ketzos Hashulchan 142 footnote 2.
The Mishneh Berurah [336/48] rules leniently and so rules Admur above.
 Ketzos Hashulchan 142 footnote 2