I am wondering whether you are aware that you can post images of gravestones using the wonderful ViewMate feature of jewishgen. Doing so make it easy to reply, and easier for helpers to see other replies -- and to respond to them -- in a more organized and efficient manner.
Here is my reading of the entire stone, which will repeat much of what was already written, but will also be a bit different.
I will bold the actual text of the stone, to help it stand out from my remarks.
[The top of the stone has the word "HaLevi", meaning that the deceased was a Levite. Levites trace their ancestry back, son to father, to Levi, one of the 12 sons of Jacob. Levites had specific functions in the Temple services, still have special status today, and assist the Priests (Cohanim) when they prepare to bless the congregation.]
a dear and honored man
the learned one
[who died at a] young age, our teacher the rabbi [I beg to differ with the person who responded that the abbreviation that appears, which represents the Hebrew words "Moreinu HaRav", usually does not indicate that the person was a rabbi. On the contrary: this abbreviation means exactly that: he was a rabbi. Unfortunately, this abbreviation occasionally appears when it should not. The excellence of the rest of the text on this stone makes me feel strongly that he was indeed a rabbi. It does not necessarily mean that he had a pulpit and led a congregation, but it definitely means that he had received rabbinical ordination].
SHMARYAHU [I see that others have read it as Shmaryah. Both of these are valid names. However, there is an apostrophe on the stone after the last letter, which usually indicates an abbreviation, meaning that at least one letter has been omitted.]
son of Menachem Aryeh [here, too, the middle name is not spelled out; there is an apostrophe to indicate the missing last letter], may his light shine [in other words, the father was still alive].
Rivnik/Ribnik, died on the second day of the holiday of Pesach [Passover]
[rather than give the date of death using the standard month+day, it is here given in terms of the holiday upon which he died. The calendar date of the 2nd day of Passover is always the 16th day of the month of Nisan]
of the year 688 [I am reading the year differently from others; zooming in on the date indicates clearly that the last digit is an 8, rather than a 5]
according to the small count [in other words, the thousands digit -- the '5' -- does not appear in the year, but is understood]
[The 2nd day of Passover of the year 5688 began at sunset on April 5th, 1928, and ended at sunset on the 6th.]
May his soul be bound up in the bond of life.
Brooklyn, New York, USA