Hitch (and others): Bighouse has pegged the kingdom parables of Matt. ch. 13.
Consider that Jesus explained two of them (vs 18-23, 37-43). If the focus would have changed wouldn't our Lord have said so. Especially since the disciples understood the other parables without explaination (v 51).
Leavened bread was prescibed for peace offerings in Lev. 7:13. All other instances of peace offerings is represented by animal sacrifice and/or the fat thereof. As for Lev 7:13; "Leaven, commonly used at social feasts, was permitted in the thank offering because this was the spontaneous expression of devotion from lives that were not entirely rid of sin and evil in every case(v 13). It taught that everything eaten is sanctified by the Word of God and prayer. (1Tim. 4:4-5; 1Cor. 10:23, 30) and that food which enters the stomach does not defile a man (Mt. 15:11)." --Dake commentary on Lev. 7:13
As for the 'foul fowls', certainly the dove denotes the Holy Spirit, but here again if we keep the train of thought being taught by the Lord in Matt. 13, these particular birds must be evil.
As for Strongs ref. 3772; it could mean --- the sky, right?
Consider this. The kingdom parables are taught as a warning to the Church. Dovetail this with the letters to the churches in Rev. and the endtime teaching on false teachers and doctrine. The church will be and has been infultrated by false doctine. Now reread the kingdom parables and consider what the Lord is warning. "Who hath ears to hear, let him hear." v.9.