~ The Mekhilta de-Rabbi Shimon (Measures, Rules of R. Simon) is a halakhic midrash on Exodus from the school of R. Akiba. Rabbi Shimon is identified with R. Shimon bar Yohai. He is probably the author. However, the frequent citation of his son Elazar makes it plausible that he edited his father's midrash. Though no midrash of this name is mentioned in the Talmud, it was known by other names including Mekhilta Ahirta de R. Shimon or Mekhilta Aheret. Today it has disappeared, but some extracts from it have been preserved and collected together as Midrash ha-Gadol. Shimon Bar Yochai died on year 160 CE. It is not clear when Eleazar ben Shimon died.
~ Mekhilta de-Rabbi Ishmael (Measure, Rule of R. Ishamel) is a halakhic midrash to the Book of Exodus. Composed in Talmudic Israel/Babylon (135 CE). Neither the Babylonian nor the Jerusalem Talmud mention the Mekhilta by name, but it is referred to once as She'ar Sifre debe Rab. The first person to mention the Mekhilta by name was the author of the Geonic work Halakhot Gedolot. Another Geonic name for it was Mekhilta de-Erez Yisrael. The author, or more correctly the redactor, of the Mekhilta cannot be ascertained. Some scholars thought it was R. Ishmael ben Elisha, R. Akiba's contemporary. The present Mekhilta cannot, however, be the one composed by R. Ishmael, as is proved by the references in it to R. Ishmael's pupils and to other later tannaim. It must be assumed, therefore, that R. Ishmael composed an explanatory midrash to the last four books of the Torah, and that his pupils amplified it.
Midrash Aggadah is a collection of midrashim published in 1894 by Solomon Buber, who worked from manuscripts. The age of that collection is put to no older than year 1000.