There are seven cases of Rhym* + Ryhm* in OhioLINK. Or so I think. (No, no, I jest. In fact I know. I did that so the rhyme would go.) The Boolean AND search may work best here, by the way; a simple search on Ryhm* alone got 26 results, most of which were for foreign words and personal names (mainly the marvelously monikered Inge L. Ryhming). If your catalog is not as large as OhioLINK's, you could try searching on just Ryhm* (limited, perhaps, by certain NOT operators). Or else search separately on Ryhme (two in OhioLINK) and Ryhmes (five). Nicholson Baker, whom librarians tend to passionately either love or hate, has a new book-related book out called The Anthologist. It concerns a writer whose task it is to come up with an introduction to an anthology of poetry. Specifically, that is, to poems that rhyme. I like that premise since I have always enjoyed the musicality of such poetry and the way it requires working within the constraints of the form. (To me, free verse often seems like little more than prose without the grammar.) Perhaps rhyming poetry is too often associated with the nursery. But then again, you've got The Rime of the Ancient Mariner, with an iambic scheme of ABCB, along with a lot of other great stuff. So check out The Anthologist, a book about rhymes, which got a good review in the New York Times!
(Nicholson Baker, 2007, from Wikimedia Commons.)