In English
Generally, lovers of Rumi's poetry will write and send a single line from a poem they have read somewhere, usually a poem they were very attracted to, and ask which book it came from. This presents difficulties (unless it is a quatrain-- see below). If the line is from one of Rumi's "longer poems" (longer than four half-lines), then it is from a ghazal, or ode. Unfortunately, there is no data base of such poems available via this website (and even sending the first line will probably not help, unless it happens to be very familiar).
Oftentimes the source of the poem is from one of the various books containing versions by Coleman Barks. Chances are good that the poem has been re-published in Barks' popular anthology of his renditions, "The Essential Rumi," 1995. In this case, it may be found in the index of first lines at the end of the book (even by going to a bookstore, in the case of someone who doesn't have a copy or doesn't wish to buy one).
What is needed is a group of volunteers who have access to most of the popular Rumi books who would be willing to scan all those hundreds of pages into a word-processing program. Such a group could then establish a website and answer Rumi poem search requests. (The data base would need to be retained by a private group, in order to respect copyright laws.)
If the line is from a "short poem" of four (half) lines, then it is probably a quatrain [rubâ`i] (or it may be part of a ghazal). In this case, feel free to send an e-mail to this website and type "Divan Search" in the subject area. Success is most likely if the first line (or even the first few words of the first line) of the English rendering is sent. If not, a computer search of key words may possibly be successful in determining which particular quatrain attributed to Rumi it is as well as the name of the translator or version-maker (with book source and page number). If you want to know if a particular Rumi quatrain you love has been translated or versioned by someone else, this information may also be available.
In Persian
If the poem is a ghazal, all that is needed is the first line (transliterated-- the Persian words typed out, using any method), or even the last few words of the first line plus the first word. In this case, ghazals can be found which are in Foruzanfar's edition of the ghazaliyât, based upon the earliest manuscripts, as well as the "Foruzanfar number" of the poem.
If the poem is a ghazal from one of the many books translated from Turkish by Nevit Ergin ("Dîvân-i Kebîr," Meters 1- 13) and the request is for the corresponding ghazal number in Foruzanfar's edition, this can be found in most cases. Send an e-mail to this website and type "Divan Search" in the subject area.
If the poem is a rubâ`i, all that is needed is a transliteration of any of four half-lines. The true "Foruzanfar number" of the quatrain can be given if it is a rubâ`i from his authentic edition (Volume 8). If the quatrain is from the inferior one-volume commercial edition ("Kulliyât-i Dîvân-i Shamsî Tabrîzî," published by Amîr Kabîr), then it may be from the "pseudo-Foruzanfar" edition of the quatrains contained in that volume. Quite a few of these quatrains are not in the authentic Foruzanfar edition. And the ordering and numbers of the rubâ`yât are completely different in both books.