JOEL - The Book of Mormon does not give this prophet's name; but Joseph Smith later identified it as Mahonri Moriancumer (Times and Seasons 2 [1841]:362)
"While residing in Kirtland Elder Reynolds Cahoon had a son born to him. One day when President Joseph Smith was passing his door he called the Prophet in and asked him to bless and name the baby. Joseph did so and gave the boy the name of Mahonri Moriancumer. When he had finished the blessing he laid the child on the bed, and turning to Elder Cahoon he said, the name I have given your son is the name of the brother of Jared; the Lord has just shown (or revealed) it to me. Elder William F. Cahoon, who was standing near, heard the Prophet make this statement to his father; and this was the first time the name of the brother of Jared was known in the Church in this dispensation."(Juvenile Instructor, Vol. 27 [May 1, 1892]:282)

As far as I am concerned, Joseph's word is as good as scripture.
It is logical to assume that in the following scripture the name of a place called Moriancumer could have been named after the brother of Jared.
"And now I proceed with my record; for behold, it came to pass that the Lord did bring Jared and his brethren forth even to that great sea which divideth the lands. And as they came to the sea they pitched their tents; and they called the name of the place Moriancumer; and they dwelt in tents, and dwelt in tents upon the seashore for the space of four years. (Ether 2:13)