1. First Gas BBQ Grill: The very first gas grill was invented and patented by George Stephen of Weber-Stephen Products Co. in Indiana on May 20, 1980. It revolutionized the barbeque world and is now considered the standard for outdoor cooking.

2. Hoosier Poet: James Whitcomb Riley, an Indiana native, was born on May 20, 1849. Known as the "Hoosier Poet," Riley's works were widely popular in the late 19th and early 20th century for their humorous and sentimental depictions of rural life.

3. Stagecoach Robbery: One of Indiana's most notorious stagecoach robberies occurred on May 20, 1838, near Bedford. The thieves made off with $950 in cash and jewelry, which was a significant amount of money at the time.

4. Indiana State Constitution: On May 20, 1851, a constitutional convention was held in Indianapolis to draft a new constitution for the state of Indiana. The resulting document remains the state's governing document to this day.

5. Markland Dam Completion: The Markland Dam, located on the Ohio River between Indiana and Kentucky, was completed on May 20, 1964. This massive engineering project was instrumental in controlling the river's flow and preventing floods in the region.