Saturday’s mail brought an unexpected windfall to stunned residents around Winooski — two crisp $100 bills, along with a cryptic note.

Each envelope, postmarked from Burlington, contained the same amount of cash and the brief message, printed on a small sheet of paper headlined “RIPPLES.”

“Take one and pass one," the note read. "If you really need em, keep em both.”

Norah Kell was shocked when she opened her envelope. “I thought maybe it was a scam,” she said.

Jeffrey Thomas was amused after opening his. “It’s a fun little mystery,” he said. Thomas said his letter carrier told him he’d been dropping off similar missives all day. The U.S. Postal Service did not immediately respond to a request for comment.

One person posted a photo of their letter on Reddit, which led to speculation about its origin. Another user guessed that the message was referencing the classic Grateful Dead song “Ripple,” which has the lines:

Reach out your hand, if your cup be empty
If your cup is full, may it be again

Another person asked: “How do I sign up for this free cash?” Two Reddit users wrote that they, too, had received the letter.

The sender and their motives remain unknown, as does the number of people who received a letter. Some who did have interpreted the message as an invitation to donate money where it's needed.

Thomas said he gave $100 to the Winooski Memorial Library and another $100 to the Boys & Girls Club.

Kell has donated some of her cash to Lund in honor of a family friend who passed away recently. She's contemplating what to do with the rest. “I feel a lot of responsibility to get that money to where it needs to go,” she said.