The Tulip Craze
Via Encyclopedia Britannica, a look back to when there was a mania for tulips:
The craze reached its height in Holland during 1633–37. Before 1633 Holland’s tulip trade had been restricted to professional growers and experts, but the steadily rising prices tempted many ordinary middle-class and poor families to speculate in the tulip market. Homes, estates, and industries were mortgaged so that bulbs could be bought for resale at higher prices.