Santa was good to the Mayo Clinic last year.

Benefactors showered the clinic in 2016 with noncash contributions worth more than $21 million, with gifts coming in the form of artwork, collectibles, residential real estate and even a wheelchair-accessible van.

The annual total was the highest listed on regulatory filings since 2012.

Behind many gifts lie poignant stories of caregiving and generosity, clinic officials say, including one involving baseball legend and former Mayo Clinic patient Lou Gehrig.

"Many of our benefactors are patients, so they've received a first-person experience of having care here," said Matt Dacy, director of Heritage Hall, a Mayo Clinic museum that houses some of the historical artifacts that get donated to the clinic. "I think they perceive that what we can offer them today came from somebody else, and they want to advance that."

Most philanthropy comes in the form of cash at Mayo Clinic, which last year posted income of $475 million on $11 billion in revenue. But some donors opt to give items of value.

Among Minnesota nonprofit groups, Mayo Clinic often has one of the more extensive lists of noncash contributions when such gifts are disclosed in its annual filing with the IRS each November.

In 2016, works of art donated to Mayo were sold at auction for $18,000. Donors gave the clinic $4.9 million worth of residential real estate including six homes and four vacant lots that either have been sold or will be.

Mayo received $13 million worth of publicly traded securities, and another $2.8 million in the form of other investments. The van was valued at $36,500 and is being used at Mayo Clinic Health System's hospital and clinic in Osseo, Wis.

The most recent IRS filing lists one historical artifact, but doesn't list a value for the item. Dacy, the museum director, said he wasn't familiar with that particular gift, but recalled the story of another artifact, from 2014.

A Rochester man and his daughter gave the clinic a baseball that had been signed by Lou Gehrig, the legendary Yankees first baseman whose career was dramatically cut short by an illness called amyotrophic lateral sclerosis, or ALS. Gehrig was diagnosed with the ailment at Mayo Clinic in 1939, and the condition to this day is referred to as Lou Gehrig's disease.

During his weeklong evaluation in Rochester, Gehrig spent time giving batting clinics to teenagers who played on the local American Legion team, Dacy said. He befriended one of those teenagers, Bob Tierney, who asked Gehrig to sign his lucky baseball.

"Bob tells the story that he saw Mr. Gehrig cradle the baseball in his arm, because, of course, he had tremors at that point — he was frail," Dacy said. "But he executed a perfect signature."

Tierney kept the ball for 75 years, and sold it at the end of his life to a Rochester business executive. The man and his daughter opted to donate the baseball to Mayo Clinic in 2014, and it became the centerpiece of an exhibit at the clinic this year.

"We can't keep all objects that are given to us — there isn't the space," Dacy said. "But in certain circumstances the object is so emblematic of our mission that we keep it as a point of education and inspiration."

Christopher Snowbeck • 612-673-4744 Twitter: @chrissnowbeck