Or: Was Sulla’s grass crown a fake?
Pliny the Elder in his Natural History has a chapter on the corona graminea, The Grass Crown: How Rarely It Was Awarded, Book XXII, Chap. 4. (3.) Google Books.
If you scroll down to Page 394, you see that Pliny casts some doubt on Sulla’s veracity on receiving the grass crown, “if there is any truth in this statement.”
Paul Moore in Two Notes on Pliny's Natural History, The Classical Review, New Ser., Vol. 23, No. 1 (Mar., 1973), pp. 13-14, (JSTOR, limited access) discusses this and a similar comment by Pliny on Varro and the corona navalis, which Varro supposedly won from Pompey during the war against the pirates (N.H. vii. 115 and xvi. 7), whereas other ancient sources say that Agrippa, who received the corona navalis from Augustus,was the only one to have done so. This latter information, according to Moore, came possibly from Varro's autobiography. (These texts are supposedly at Perseus, but as so often, I can't access them, nor are they on Eason.)
Moore writes that “both of the instances focus attention on the credibility of claims made in autobiographies,” and in Sulla’s case he notes “the silence of the authorities on any serious difficulties faced by the Romans at Nola.”
Gellius (Book V, 6, 9) too mentions only Fabius Maximus in connection with the grass crown.