Bruce R. McConkie, Mormon Doctrine, p. 577, under Plurality of Gods
“Three separate personages -- Father, Son, and Holy Ghost -- comprise the Godhead. As each of these persons is a God, it is evident, from this standpoint alone, that a plurality of Gods exists. To us, speaking in the proper finite sense, these three are the only Gods we worship. But in addition there is an infinite number of holy personages, drawn from worlds without number, who have passed on to exaltation and are thus gods.”
John A. Widtsoe, Evidences and Reconciliations, p. 65
“This revealed doctrine on the composition and nature of the Godhead teaches that there are at least three Gods. The prophet Joseph Smith, challenged by unbelievers that he taught a plurality of Gods, replied in a sermon, ‘I will preach on the plurality of Gods. I have selected this text for that express purpose. I wish to declare I have always, and in all congregations when I have preached on the subject of the Deity, it has been the plurality of Gods. It has been preached by the elders for fifteen years.’ ”
Encyclopedia of Mormonism Vol. 2, under Godhead
“On June 16, 1844, in his last Sunday sermon before his martyrdom, Joseph smith declared that ‘in all congregations’ he had taught the ‘plurality of Gods’ for fifteen years: ‘I have always declared god to be a distinct personage, Jesus Christ a separate and distinct personage from God the Father, and that the Holy Ghost was a distinct personage and a Spirit: and these three constitute three distinct personages and three Gods.’”
It should be evident that early LDS leaders (including Joseph Smith) believed in and taught a plurality of gods. The Encyclopedia of Mormonism was published in 1992 and therefore reiterates and agrees with these early teachings.
(If any questions, you may want to look up the references and read them in context.)