As a child most of us are taught that nothing rhymes with orange. But now grown up I discover that there are rhymes, for example, on RhymeZone, they show that sporange and gorringe are rhymes. (I'm not sure if this is a question that is allowed to be asked on this site, if it isn't I will remove it.) But why are there rhymes now and not before? These words are only rare words but does that make them a valid rhyme or is it just that they simply don't perfectly rhyme?
That very same RhymeZone website says that "gorringe" is
A surname (very rare)
Although sporange, a variant of sporangium, is an eye rhyme for orange, it is not a true rhyme as its second syllable is pronounced with an unreduced vowel [-ændʒ], and often stressed.
I don't think either of those invalidates what you learned in grade school.
As a child most of us are taught that nothing rhymes with orange.
Actually, that may be what you learned, but I'm not sure that's exactly what you were taught. Sometimes we hear a teacher say something like: there are no English words that are exact rhymes with 'orange', but somehow we oversimplify that in our minds, and fail to acknowledge how that wouldn't necessarily preclude near rhymes or bent words, or proper nouns, compound words or enjambments. That same Wikipedia article lists a few examples; I'll close with one of the more ingenious ones:
The four engineers wore orange brassieres.
And yes, "more ingenious" intentionally rhymes with "orange genius."