The Downside of Memory

I thought I had the perfect poem for today--it was one from a Western Lit survey, that I remember touching me at the time I read it. More often than any particular bit of the poem--no particular phrase or image though I have a vague recollection of the poem's framework--it's the emotional impact on me I remember. So I dug out the book and I looked for the poem. And I found nothing. None of the poems by the author match my memory. Did I make up a poem? Did I convince myself that I'd read it and loved it?