The plates were supposed to have been buried in the ground. How could an angel have taken them "back"? That implies that the angel gave him them first.
So an angel took them back? Pretty convenient.
How did he find them in the first place?
http://scriptures.lds.org/en/js_h/1
I’m sure the antis on this thread will point you in other directions, but this is the official canonized version. Not even an “intro” by McConckie, this is in Joseph Smith’s own words.
“How could an angel have taken them “back”? That implies that the angel gave him them first...How did he find them in the first place?”
From http://scriptures.lds.org/en/js_h/1/27-59#27
“The box in which they lay was formed by laying stones together in some kind of cement. In the bottom of the box were laid two stones crossways of the box, and on these stones lay the plates and the other things with them.I made an attempt to take them out, but was forbidden by the messenger, and was again informed that the time for bringing them forth had not yet arrived, neither would it, until four years from that time; but he told me that I should come to that place precisely in one year from that time, and that he would there meet with me, and that I should continue to do so until the time should come for obtaining the plates...At length the time arrived for obtaining the plates, the Urim and Thummim, and the breastplate. On the twenty-second day of September, one thousand eight hundred and twenty-seven, having gone as usual at the end of another year to the place where they were deposited, the same heavenly messenger delivered them up to me...”
“So an angel took them back? Pretty convenient.”
It’s only convenient for those looking for an excuse to reject it. I’m sure that even if they were on display in Utah that such people would find some other excuse. Meanwhile there was no further need for Joseph and his family to be continue to be at risk from the kind of men who were trying to find them and take them for their worldly value.