No

Jerry gave a great answer. Notice what he writes about how spelling is irrelevant to the rhyme. In English, a rhyme requires that the accented vowel and all subsequent sounds (consonants and vowels) be the same. Likewise, the stress pattern must be the same. If the consonants are different, it is only an assonant rhyme. Assonant rhyme works well in other languages (such as Spanish), but is not typically considered a strong enough rhyme in English.

No, they do not rhyme. I'm sitting here trying to think if anything rhymes with lemon. Ok, I thought of something - Though spelled different "Yemen" rhymes with lemon. Melon = Helen, Felon, Ellen. Very good question as I never realised how hard it would be to come up with something for "lemon". I Hope this helped, Jerry (Teacher/Tutor)

You could definitely pull it off in a song or something, but I wouldn't consider it perfect, just because the two last syllables don't rhyme. A better rhyme for lemon would be "swimmin' " or "persimmon" And a better rhyme for melon would be "swellin' " or "tellin' ". Others might disagree :)