Daf Yomi 114b - Naomi as prototype of Believed Woman

Unlikely, but still why not put the idea out there.

{Yevamot 114b}
Mishna:

האשה שהלכה היא ובעלה למדינת הים
שלום בינו לבינה ושלום בעולם באה ואמרה מת בעלי תנשא מת בעלי תתיבם
שלום בינו לבינה ומלחמה בעולם קטטה בינו לבינה ושלום בעולם באה ואמרה מת בעלי אינה נאמנת
רבי יהודה אומר לעולם אינה נאמנת אא"כ באה בוכה ובגדיה קרועים
אמרו לו אחת זו ואחת זו תנשא:

A woman who went with her husband to an overseas country.
If there was peace between them and peace in the world, and she comes back and says "my husband died," she may remarry, or "my husband died," {and there are no children} she may undergo yibbum.
If there was peace between them and war in the world, or arguments between them and peace in the world, if she came back and said "my husband died," she is not believed.
Rabbi Yehuda says: She is never believed unless she comes crying, with her clothing ripped.
They said to him: Both this and that may remarry.

{Yevamot 116b}

בית הלל אומרים לא שמענו אלא הבאה מן הקציר בלבד
אמרו להן ב"ש אחד הבאה מן הקציר ואחד הבאה מן הזיתים ואחד הבאה ממדינת הים לא דברו בקציר אלא בהווה
חזרו ב"ה להורות כדברי ב"ש:

Bet Hillel say: We only heard regarding one who came from the {wheat?} harvest.
Bet Shammai say: Whether the one who comes from the harvest, or from the olives {picking}, or who came from an overseas country. They only spoke regarding the harvest because of the common case.
Bet Hillel retracted in order to rule like the words of Bet Shammai.

What is the basis for this requirement that the woman appears in mourning when telling over her loss? What is the basis for coming from the harvest? What is this famous incident?

Tosafot suggests that during the wheat harvest, heatstroke is common and thus we might be more prone to believe that he died, and this is (I guess) the common case of causing death.

I may as well be fanciful, and suggest another common case, which Bet Shammai and Bet Hillel might be referring to -- Rut and Naomi's return from Sedei Edom. Ruth was a case of peh sheAsar peh sheHitir, for she was the source that she had married, as well as that she was widowed. Naomi, though, they knew was married when she left. (There are also issues in that their relationship precludes one testifying on the behalf of the other.)

We see at the end of the first perek of Rut:

יט וַתֵּלַכְנָה שְׁתֵּיהֶם, עַד-בּוֹאָנָה בֵּית לָחֶם; וַיְהִי, כְּבוֹאָנָה בֵּית לֶחֶם, וַתֵּהֹם כָּל-הָעִיר עֲלֵיהֶן, וַתֹּאמַרְנָה הֲזֹאת נָעֳמִי.	19 So they two went until they came to Beth-lehem. And it came to pass, when they were come to Beth-lehem, that all the city was astir concerning them, and the women said: 'Is this Naomi?'
כ וַתֹּאמֶר אֲלֵיהֶן, אַל-תִּקְרֶאנָה לִי נָעֳמִי: קְרֶאןָ לִי מָרָא, כִּי-הֵמַר שַׁדַּי לִי מְאֹד.	20 And she said unto them: 'Call me not Naomi, call me Marah; for the Almighty hath dealt very bitterly with me.
כא אֲנִי מְלֵאָה הָלַכְתִּי, וְרֵיקָם הֱשִׁיבַנִי יְהוָה; לָמָּה תִקְרֶאנָה לִי, נָעֳמִי, וַיהוָה עָנָה בִי, וְשַׁדַּי הֵרַע לִי.	21 I went out full, and the LORD hath brought me back home empty; why call ye me Naomi, seeing the LORD hath testified against me, and the Almighty hath afflicted me?'

Also, coming back from a harvest is the next pasuk:

כב וַתָּשָׁב נָעֳמִי, וְרוּת הַמּוֹאֲבִיָּה כַלָּתָהּ עִמָּהּ, הַשָּׁבָה, מִשְּׂדֵי מוֹאָב; וְהֵמָּה, בָּאוּ בֵּית לֶחֶם, בִּתְחִלַּת, קְצִיר שְׂעֹרִים.

22 So Naomi returned, and Ruth the Moabitess, her daughter-in-law, with her, who returned out of the field of Moab--and they came to Beth-lehem in the beginning of barley harvest.

though it is a barley harvest.

On the day of Ruth's customary yibbum, it was at the end of the wheat harvest, as we read (second perek):

כג וַתִּדְבַּק בְּנַעֲרוֹת בֹּעַז, לְלַקֵּט--עַד-כְּלוֹת קְצִיר-הַשְּׂעֹרִים, וּקְצִיר הַחִטִּים; וַתֵּשֶׁב, אֶת-חֲמוֹתָהּ.

23 So she kept fast by the maidens of Boaz to glean unto the end of barley harvest and of wheat harvest; and she dwelt with her mother-in-law.