In 1961, Sports Illustrated published a photo taken by a SAMOS satellite. It clearly showed a golf ball sitting on a golf green. SAMOS was public knowledge, but I have no idea how the magazine got hold of a photo from such a sensitive program.
Sports Illustrated? Maybe ... but spy satellites were not tracking Russian submarines in March 1968. There were undoubtedly spy satellites aloft, however, they were few and far between ... and most of those were Russian.