ויטע ה' אלוקים גן בעדן מקדם, “And God planted a garden in Eden מקדם.” Rashi explains that the Torah is merely describing the location in Eden where the garden was placed.
אונקלוס explains מקדם with the term מלקדמין, “From before.” Yonatan ben Uziel is more specific: עולם גינותא מעדן לציקיא קדם בריית עולם,“ [Hashem established] a garden from עדן for the righteous even prior to the creation of the world.”
Ramban subscribes to the interpretation of אונקלוס and explains that the Torah is teaching us that even prior to the command of תדשא הארץ דשא “Let the earth give forth grass,” Hashem had already commanded that a garden should appear in Eden.
The Pasuk therefore is not teaching us that the garden was in the East but rather that the garden was planted prior to the creation of any other greenery on the third day of creation.
By creating a home for Adam prior to anything else on the third day, Hashem is demonstrating the importance of the relationship that he hopes to establish with man. Man is created in the image of God and therefore receives special attention.
With this approach to the Pasuk we can understand the following Beracha in the Sheva Berachot: שמח תשמח רעים אהובים כשמחך יצירך בגן עדן מקדם. We charge the חתן and כלה (Bride and Groom): “Rejoice!” and the simile is used: “Rejoice as your creator made you happy in בגן עדן מקדם.” If מקדם meant east it is most certainly a superfluous term. Rather, we are blessing the חתן and כלה that when Hashem sought to establish a special relationship with Adam, He did so by creating a garden especially for him prior to creating anything else. So too, the new חתן and כלה should demonstrate their love for one another throughout their lives by giving to one another in a fashion that creates an everlasting bond between them.