Back in 2011, some broken ninth-century pottery with hiragana written on it was unearthed at the site of Fujiwara no Yoshimi's residence. It wasn't clear what the writing on it meant, and the official best guess was that it was "いくよしみすらキれ□□ち" (ikuyo shimi sura kire ___ ___ chi - the blanks are illegible or missing), which is basically nonsense. But, good news! Professor Nanjō Kayo 南條佳代 of Bukkyō University (specialty: kana calligraphy of the Heian period) may have solved the mystery.

According to Nanjō's analysis, the shards were misread. You can see a visual summary here, but basically her argument is that the shard actually says "いくよしもあらし わかみを" (ikuyo shi mo arashi / waka mi wo), which, with voicing added, is a fragment of this Kokin waka shū poem (author unknown):

いく世しもあらじわが身をなぞもかくあまのかるもに思ひみだるる
Ikuyo shimo/ araji wa ga mi wo/ nazo mo kaku/ ama no karu mo ni/ omoi-midaruru
"I surely will not live forever; why then, must my thoughts be as tangled and snarled as the seaweed the fisherwomen harvest?"

As someone still very much struggling with the vast mass of tangled seaweed that is premodern (particularly pre-Edo) Japanese orthography — not to mention all the poems I'm supposed to have memorized before I read any of the subsequent literature — it's very reassuring to learn that even the real experts need a few years to think about these things.