The first time the Toronto Blue Jays sent a player to Oakland was in February 24, 1977, when the Blue Jays acquired Ron Fairly while sending Mike Weathers and cash the opposite way (after they drafted him in the expansion draft).
Both teams usually have ulterior motives when it comes to trading, as the Blue Jays tend to spend when on a playoff run, while the Athletics trade star players away before they are due for a pay raise (hooray for stingy spending ownership). We’re seeing the opposite of that scenario play out this season, but things have been different throughout the 43 years of this franchise.