We read of his fate but we are not told if he was buried or who may have buried him. We can presume Adam and Chava grieved and gave his body a resting place but that is speculation. Is there drash about this? Sources?
There are a few Midrashic sources that tell us that the animal kingdom seemed to take care of things:
In Pirkei D'Rebbi Eliezer 21 it notes that firstly his sheepdog did 'shmira' over the body, and then a raven showed Adam what to do.
הכלב שהיה משמר צאנו של הבל הוא היה שומרו מכל חית השדה ומעוף השמי' והיו אדם ועזרו יושבים ובוכים ומתאבלי' עליו ולא היו יודעים מה לעשות להבל שלא היו נהוג' בקבורה בא עורב אחד שמת לו אח' מחבריו לקח אותו וחפר באר' וטמנו לעיניהם אמ' אדם כעורב אני עושה מיד לקח נבלתו של הבל וחפר בארץ וטמנה
The dog which was guarding Abel's flock also guarded his corpse from all the beasts of the field and all the fowl of the heavens. Adam and his helpmate were sitting and weeping and mourning for him, and they did not know what to do (with Abel), for they were unaccustomed to burial. A raven (came), one of its fellow birds was dead (at its side). (The raven) said: I will teach this man what to do. It took its fellow and dug in the earth, hid it and buried it before them. Adam said: Like this raven will I act. He took the corpse of Abel and dug in the earth and buried it. (sefaria Translation)
Also refer to Yalkut Shimoni, Bereishis 38 for the same idea.
In Bereishis Rabbah 22:8 it adds:
, אָמַר רַבִּי אֶלְעָזָר בֶּן פְּדָת עוֹפוֹת הַשָּׁמַיִם וְחַיּוֹת טְהוֹרוֹת קְבָרוּהוּ, וְנָתַן לָהֶם הַקָּדוֹשׁ בָּרוּךְ הוּא שְׂכָרָן שְׁתֵּי בְּרָכוֹת שֶׁמְבָרְכִים עֲלֵיהֶן, אַחַת לִשְׁחִיטָה וְאַחַת לְכִסּוּי הַדָּם.
Rabbi Elazar son of Pedas said the birds of heaven and the kosher wild animals buried him, and Hashem rewarded them with two blessings - one, ritual slaughter (shechita) and one, the covering of their blood.
The answer is in Midrash Tanchuma, Bereshit 10:2:
After Cain slew Abel, the body lay outstretched upon the earth, since Cain did not know how to dispose of it. Thereupon, the Holy One, blessed be He, selected two clean birds and caused one of them to kill the other. The surviving bird dug the earth with its talons and buried its victim. Cain learned from this what to do. He dug a grave and buried Abel. It is because of this that birds are privileged to cover their blood.