The original filed case would have been "Government v. Item", with the government (plaintiff) suing the item (defendant), not the other way around. But these are appellate cases, and the title convention there is "Appellant v. Respondent", regardless of who was the original plaintiff or defendant. So in each case, the item presumably lost in some lower court and is now appealing to SCOTUS.
Taking 62 Cases of Jam as an example and chasing the citations, the original case in US District Court for the District of New Mexico was United States v. 62 Cases, 87 F. Supp. 735 (D.N.M. 1949). The government sought to condemn the jam on the grounds that it was only 25% fruit, where federal standards for jam required that it must contain at least 45% (or more depending on the type of fruit). The District Court dismissed the "libel" on the grounds that the product was clearly labeled "imitation".
The government appealed to the Tenth Circuit (183 F.2d 1014 (10th Cir. 1950)); here the case was still titled "US v. 62 Cases" since the United States was the appellant; appeals cases are always titled "Appellant v. Respondent". The circuit court reversed, ruling that since it looks and tastes like jam, it has to meet the standards for jam, its label notwithstanding, and ordered the jam to be condemned.
The jam petitioned for certiorari to the US Supreme Court, (340 U.S. 593 (1951)), and now for the first time the title of the case is "62 Cases of Jam v. US" since the jam is now the petitioner. Again, "Petitioner v. Respondent" is the norm. As the defendant party was "62 Cases of Jam" throughout the lower courts, it wouldn't make sense to change it to "Fred Smith, Owner of 62 Cases of Jam" at this point.
SCOTUS reversed, and the jam was finally exonerated, free to resume its ordinary jammy activities.