At first glance, it would seem that the mitzva of bringing the bikkurim (first fruits) to the Temple belongs to the category of mitzvot of "reishit" (first) – a category which includes teruma, terumat ma'aser, challa, the first fleece, the firstborn of animals, the redemption of firstborn children, etc. However, the mitzva of bikkurim is unique among the mitzvot of "reishit" owing to a few of its important details- the "bikkurim declaration", the obligation to bring only from the "seven species" of Eretz Yisrael, among other specific details. What is the reason for the uniqueness of the mitzva of bikkurim? 

Bikkurim - First Fruit
Courtesy of the Virtual Beit Midrash, Yeshivat Har Etzion