The color green is almost exclusively used in connection with plants in the Bible, and the meaning is closely connected to the meaning of plants as well. Plants, in general, represent facts, knowledge that we can gather from the world. Green plants are ones that are alive and growing. Since life represents love and goodness, it makes sense that green plants are facts that have the potential for good use. It also indicates that they are the kinds of things we learn through directly through our senses, since to identify green plants we need to actually see the greenness.

(References: Apocalypse Explained 507; Apocalypse Revealed 426; Arcana Coelestia 7691)

8418. 'And gather the thing of a day in its day' means continually, in proportion to need. This is clear from the meaning of 'gathering' as receiving, for when 'raining' means flowing in - that is to say, good from the Divine flowing in - 'gathering' means receiving, because the one activity goes with the other; from the meaning of 'the thing' as the object to which it refers, in this instance the bread or manna from heaven; and from the meaning of 'a day in its day' as continually, in proportion to need. Continually is meant because they received the manna daily (for the meaning of 'daily' is continually, see 2838); and in proportion to need is meant because they were to gather as much each day as they were going to need and no more, which for each person was an omen