Yes; the prewar .38 M&P and .32-20 Hand Ejector were produced with wood stocks with and without the medallions. (BTW the term used by S&W and by most collectors is "stocks" for wood ones; "grips" are rubber or plastic.) Take a look at Winchester_73's post in the following thread for pictures:
AFAIK postwar Magna stocks with the high top horn pretty much always had medallions, as did Target stocks (the larger ones) and Combat stocks (the ones with finger grooves).
I won't say that S&W "never" made any of the later stock styles without medallions, because the only hard and fast rule about vintage S&Ws is that there are no hard and fast rules. However, IMHO it's fair to say that if you have a set without medallions, they are probably reproductions.
If the gun was made prior to the mid 1970s, it should have the numerical portion of the serial number inside the RH stock panel. (Alphabetical prefixes were normally omitted.)