By Bill Shields

SANDWICH (CBS) – There’s a patriotic mystery on the Cape.

For the past three years on Patriots Day, someone has been surprising homeowners in a Sandwich neighborhood with American flags next to their mailboxes.

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No one seems to know who’s responsible.

It started two years ago, just hours after the bombs went off near the Boston Marathon finish line.

This year, the flags appeared during the night, so neighbors could wake up to them on Monday morning.

For three straight Patriots Days someone has planted these flags in Sandwich. (WBZ-TV)

For three straight Patriots Days someone has planted these flags in Sandwich. (WBZ-TV)

Not one resident in the five-block area has removed a flag.

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Some ended up battered by the weather. Others disappear with the snow plows.

But every Patriots Day, a new one appears and no one seems to mind.

“I think it’s a great thing. It definitely brought a lot of pride out in the neighborhood,” resident Rob Quinn told WBZ-TV.

“I think it makes us all really happy that we have somebody that’s standing up for their country and what their beliefs are,” said resident Al Robichaud.

”It’s like a pick-me-up,” said resident Paul Anacki. “I think it’s great.”

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Everyone is curious about who is putting up these flags, but no one’s prying simply because they like it.

Bill Shields