The collection includes newspapers, paperwork, documents and items from his hotel.
Holland has worked for the Southeastern Michigan chapter of the American Red Cross for 18 years. But nothing else he has experienced in his work compares to what happened 10 years ago, when he was sent east to help provide relief to stricken New York City.
From time to time, Holland will pull the items out, take a look and remember what happened.
"Every now and then, you take a look at them to keep you grounded," he said. "You were a part of this. I'm glad we can help. I hope it never happens again, but I'm glad I was able to help out."
Holland, who currently lives in White Lake, Mich., was one of 10 individuals from the Detroit community who went to New York after the attacks and were honored Sunday at Comerica Park by throwing out ceremonial first pitches before the series finale with the Twins.
"Very touching," Tigers manager Jim Leyland said.
As part of a national day of remembrance, the Tigers donated tickets to more than 500 first responders, police officers, firefighters and their families, and they invited the servicemen and women on the field prior to the game.
The game ball was delivered by a local firefighter, and as part of the weekly "Kids Take the Field" on Sundays, the children who took the field with the Tigers prior to the game were sons and daughters of public service workers in the community.
The national anthem was sung by Peaceful Authority, a quartet of active and retired police officers from Flint.
Tigers pitcher Rick Porcello was in his middle school cafeteria on Sept. 11, 2001, when he was told by a friend what had happened. It wasn't until he got home later that day that he learned about everything.
Five Tigers players, including Porcello, and five Twins players caught the 10 ceremonial first pitches.
"I thought it was great and I thought it was absolutely necessary to remember the ones that had fallen on that day and also recognize the men and women that are doing the job now," Porcello said. "It's one of those things you never forget what happened on that day, but those people are still out there risking their lives. It was a good day overall."
As with so many people, that day forever changed the life of Holland, who lived in Oak Park at the time. Used to responding to fires or floods, Holland was told he would be heading to New York City shortly following the attacks. He was set to head there via airplane, which initially made him uneasy. But he knew he had to get there.
"The people there were probably a lot more afraid of not having what they needed than I was of getting on a plane and going over there," he said.
While there, Holland did what he always does with the Red Cross: help provide food, clothing and shelter. But while it was similar, it also was very different.
"I was so used to doing fires and floods and events that have a beginning, an active phase and [when it ends], you take off and go away," he said. "With the terrorist incident, you don't have those elements. You don't know the makeup of what's going to happen."
With the unprecedented scale of damage, there were doubts in Holland's mind that things weren't going to turn around.
"At some point, I thought, 'We're never going to be able to help these people. We're never going to be able to help this amount of people,'" he said. "But we got it done. We didn't do it by ourselves, but everyone pitched in, everyone gave something."
Holland remained in New York for about a month. A decade later, the memories are still vivid. And with that collection in his closet, he makes sure the memories won't fade away.
"Some of the people I'm here with today, I was standing next to when it happened 10 years ago," he said. "And these are the same people that went to New York City with me."
Chris Vannini is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.