Go to the "tools" section of Perseus, go to "English - Greek" or whatever it's called, type in an English word, and it will search the LSJ, Liddell-Scott, and all the Greek-English lexicons they got, for your English word, and make a list linking to the LSJ/whatever entries. Mind you, and search for a word like "olive" might lead to some Greek word where the definition is "A ceremonial clay jar made by craftsmen in [insert obscure location] ; frequently used to hold water, olive oil, or wine in religious fesitivals." I know that when I searched for "rose" I got a bunch of words meaning going up or standing up or lifting - because "rose" is the past for "rise". But I eventually I got to a word which meant "rose flower/plant".
EDIT : I went through the Perseus Greek Morphological Tool, and it did not recognize [face=spionic]morai/a[/face], so I assume that no such word existed. It is quite possible that a word like [face=spionic]mo/ra[/face] could mean either the fruit or the plant, as in English, but I am not going to assume that without evidence.
EDIT 2 - If [face=spionic]mo/ra[/face] is the word I'm looking for, here's my haiku
maxo/ntai me/la mo/ra
r(o/da t' a)/gria[/face]
Let me know if there are any grammatical errors in it - or if not, please tell me what you think the haiku is expressing, to see if it's making the point I'm trying to show.