The shape of the root is reminiscent of a spindle; therefore the Hebrew פלך would be a candidate. In this case, Yiddish would have retained the original spelling but Liebepelech is spelled ליבעפעלעך. Hence Hebrew is probably not the source. Sorry I couldn't be more helpful.
Yes, you are right, עך- (not לעך-) is a plural suffix (this suffix doesn't exist in German therefore I didn't see it immediately).
Hence, it might not be ליבע-פעלעך (as Spharadi thought) but ליב-עפעל-עך = love-apple-s. Normally, you write apple as עפל and not עפעל but as Yiddish spelling is not fixed it is possible. In German, the term Liebesapfel (=love apple; plural: Liebesäpfel) is used by Luther for mandrake in his Bible translation.
And why would you call a friut or a root a nest? That is my problem with this explanation.
EDIT: I am not saying your explanation is wrong (the explanation as "love apples" is also inconclusive, the argument I presented before contains also only circumstantial evidence). I am saying there is a gap in your explanation to be filled.
I am not able to fill the gap, mainly because the origin of the Czech word "pelech" is unknown (certainly not Slavic). "Pelech" is a colloquial and expressive word and sounds like a borrowing from German (B...loch ??) or Yiddish.
The mandrakes belong to the same family of plants as potatoes do, which made me think of the french saying "pommes de terre" - apples in the earth. Also in Swedish dialects you can hear "jordäpplen" with the same meaning. So there is a possible connection mandrakes - apples.
As Sweden is a predominantly Lutheran country, also the Swedish bible translates mandrake into "kärleksäpplen", meaning "love apples". (Makes sense since it was seen as an afrodisiac).