There is an urban legend that early (non-indigenous) Americans believed tomatoes to be poisonous. It was most notoriously given credibility by a national CBS radio broadcast in 1949:

This episode of the You are There series depicted an event purportedly held in September 1820 in Salem, New Jersey. According to the CBS broadcast, prior to this date Americans considered the tomato poisonous.

Smith, The Tomato in America, p. 3

In fact there is ample evidence that the tomato was widely eaten. For example, the third edition of the Encyclopædia britannica (1797) stated that

The tomato is in daily use; either being boiled into soups or broths, or served up boiled as garnishes to flesh-meats.

Can that really be considered a myth? Because the potato (Nightshade) plant produces tomato-like fruit which can be poisonous. So there is actually some truth to it.