The first occurrence.
And God said, “Let the earth bring forth grass, the herb yielding seed, and the fruit tree yielding fruit after its kind, whose seed is in itself, upon the earth;” and it was so. Gen 1:11
The primitive root.
pey פ ף = the mouth, thus open, blow, scatter, edge
resh ר = the head of man, thus head, first, top, beginning, man
hey ה = the man with upraised arms, thus look, reveal, wonder, worship, breath
To understand the story, we have to know something about threshing grain in ancient days:
The heads of grains are scattered on the threshing floor, a smooth, hard and level surface. An ox is led around the floor crushing the heads, opening them to reveal the seed inside. – Ancient Hebrew Lexicon
The story: Opening (pey) the head (resh) of grain which reveals (hey) the seed inside; i.e. acquiring seed. One of the nouns derived from this root is fruit, as that which the seed thus acquired produces.