1991 Donruss baseball

This is the first of three different packs I received from Dayf in a trade recently. This one is unusual because it contains only three cards. My limited experience tells me that it must have been included with something else like bread or cookies or cereal or cheese. There is no give away on the pack or cards to mark them as different, only that there is less cards.
The 1991 Donruss set has 770 cards in the base set.
The subsets included: Diamond Kings, Rated Rookies, Al and NL All Stars, MVP's.
Additional information in this post.

The pack:

Puzzle piece 40, 41, 42

#1 Dave Stieb Blue Jays