Plants in the Bible generally represent facts, knowledge that can be gleaned from the world. Plants that can serve animals as food represent facts that have the potential to be put to use, ones that can lead to something good. A pasture, then, is an area that offers a great deal of this sort of useful, life-building knowledge. "Pasture" is often used as a verb in the Bible as well; to pasture animals means teaching people facts that can help them do what is good in life.
Joshua 24:14-15
14
"Now therefore fear Yahweh, and serve him in sincerity and in truth. Put away the gods which your fathers served beyond the River, in Egypt; and serve Yahweh.
15
If it seems evil to you to serve Yahweh, choose this day whom you will serve; whether the gods which your fathers served that were beyond the River, or the gods of the Amorites, in whose land you dwell: but as for me and my house, we will serve Yahweh."
