I asked Bettina again the other day what "Jeva" meant in Lithuanian, and she said, "Traubenkirsche".
Since that's not a term I'm familiar with, I looked it up on Wikipedia, and found two interesting interwiki links: Jėva in Samogitian and Ieva in Lithuanian (actually, the interwiki link went to Paprastoji ieva). So apparently, it's spelled Ieva in modern standard Lithuanian. (And it's apparently homophonous with the name for Eve, judging by the link to Adomas ir Ieva at the top.)
In English, it's a bird cherry, FWIW, and Prunus padus in botanical Latin.