1) WHEAT AND PEACE
QUESTION: The Gemara says that one who sees wheat in a dream will see peace. Why is wheat not included with the other three things (river, bird, and kettle) that are signs of peace (56b)?
ANSWER: As the Gemara there (56b) describes, those three things are not definite signs of peace; they could be signs of peace. Wheat, on the other hand, is definitely a sign of peace, and therefore it is not included with the other three. (SEFER BEIS YOSEF to Berachos)
2) THE VINE BRANCH AND MASHI'ACH
QUESTION: The Gemara says that one who sees a vine branch, "Soreka," in a dream should expect to see the arrival of Mashi'ach. As support it cites the verse, "He ties his donkey to the grapevine, his young donkey to the vine branch" (Bereishis 49:11).
Where in this verse is there an allusion to Mashi'ach? Also, why is only the vine branch a symbol of Mashi'ach? In the same verse it also says "grapevine" ("Gefen"), and thus grapes should also be a sign that one should expect Mashi'ach! We know, however, that grapes are not a sign for Mashi'ach, because the Gemara immediately before says that grapes are a sign that one's wife will have no miscarriages!
ANSWER: The Gemara is obviously relying on the words in the previous verse, "until Shiloh comes," which allude to Mashi'ach (see Rashi to Bereishis 49:10, and Sanhedrin 98b). The MELO HA'RO'IM and RAV YAKOV EMDEN cite the verse in Zecharyah (10:8) which says, "I will scream out to them (Eshrikah) and I will gather them in when I redeem them." We see that the word "Eshrika" (which is very similar to "Soreka") is associated with the redemption. RAV ELIYAHU GUTTMACHER cites the Gemara in Chulin (63a) which derives from the verse in Zecharyah that the bird "Shrakrak" brings mercy to the world, and if it would sit on the earth and shriek, Mashi'ach would certainly come.
3) WHAT COLOR IS "TECHELES"
OPINIONS: The Gemara says that if one sees any color in a dream it is a good sign, except if he sees the color Techeles. Why is it a bad sign to see Techeles in a dream?
(a) RASHI (DH Techeles) explains that Techeles is green (see also Rashi 9b, DH Techeles, Rashi to Bamidbar 15:38, and Rashi to Bava Basra 4a, where Rashi describes Techeles as green). If one sees the color green in a dream it is a bad sign, because if someone's facial color is greenish or yellowish it is a sign that he is sick.
TOSFOS in Sukah (31b, DH ha'Yarok) cites Rashi's opinion that Techeles is green. He says that support for this opinion can be found in the Yerushalmi that says that the color of Techeles resembles that of grass. The Gemara here also seems to be a strong support for Rashi's opinion, because if Techeles is not green, why would it be a bad sign?
Most Rishonim (including Tosfos) reject Rashi's opinion and explain that Techeles is blue. If Techeles is blue, then why is it a bad sign to see Techeles in a dream?
(b) RAV YAKOV EMDEN explains that the word "Techeles" comes from the word, "Tachlis," which means "end." Techeles is a symbol of coming to an end, and therefore it is a bad sign to see it in a dream.