Visitors to Antietam battlefield in 1862 took unexploded shells home as souvenirs. The results were disastrous, and often deadly.
Deadly Souvenirs – Unexploded Shells From Antietam Proved To Be Dangerous Keepsakes

Visitors to Antietam battlefield in 1862 took unexploded shells home as souvenirs. The results were disastrous, and often deadly.
Robert Gould Shaw wrote this letter to his mother while sitting in his guard tent three miles east of Frederick, Maryland early on Christmas Day 1861.