Gifts for Reference Writers

What is the expectation for thanking the professors who have written my letters of recommendation for graduate school?

I feel like the minimum is a thoughtful, handwritten card. But I feel like maybe a small gift would be appropriate as well? What do you feel like the etiquette is?

My daughter sent a personalized thank you note via snail mail, along with a $10 Starbucks card and a decal from the school she decided to attend.

my DS found out what his LOR writing prof’s favorite liqueur/ alcoholic beverage was, and gave him a bottle.

A small gift is perfectly fine such as the ones mentioned above, but be careful to not make it seem like a bribe.

I have written many letters of reference in my 35 years as a physics professor and the best gift is the student coming to my office and thanking me while telling me where he/she will be going next year.