I wonder why nobody told me this before: whatever I learn today, I have to repeat tomorrow and the third day! If I don't do so, I will forget it, no matter how good I knew on the first day.
First I tried to go through the whole parsha, piece by piece, and after a long time, I came back to the beginning, and started everything all over. This is extremely ...
On the level of peshat, ploughing and harvesting are mentioned in Shemot 34:21.
Also, some derive the melachah of hotza'ah ("carrying") from Shemot 36:6 (see Shabbat 96b) or from Shemot 16:29 (see Eruvin 17b with Tosafot).