If a Wizard casts Blink while in the Prone position, when they enter back into the Material Plane, will they still be in the prone position?
From my interpreation of the spell, the Answer is Yes, you would remain prone.
At the start of your next turn, and when the spell ends if you are on the Ethereal Plane, you return to an unoccupied space of your choice that you can see within 10 feet of the space you vanished from.
Empahasis is mine. As it states that you return to an unoccupied space that you see within the 10 feet of you disappearing I assume that you will return to the material plane in the same condition that you left in.