It’s pretty common in the Midwest , as others have mentioned, to put some cash in the card. Most offices I worked at would have a sunshine fund or pass an envelope around when a co-worker died. When my in-laws died, we got small amounts of money in cards- but we donated it to their preferred charity. Next week we are going to the delayed funeral ( because of covid) of a cousin of a friend of mine- they were two ladies who never married and lived in a very modest condo. I’m thinking of putting $50 or so in a card and giving it to her at the service, she is having a catered lunch for about 50 people and I think the money would be useful.