Birthdays tend to be a time for celebration, but May 16 arrived heavy for Granger Smith and his wife Amber this year. The couple's late son, River Kelly Smith, would have turned 4 years old in 2020, and they didn't let the day pass without honoring his memory in a huge way.

"My earthly plan would be to be wake up my little man today with kisses and sing happy birthday to him. God had other plans," Amber says in a lengthy social media post about her little boy, who died last June after a drowning accident at the family's home in Texas.

The Smiths have kept River's spirit alive through the River Kelly Fund, a means of helping others in need via donations, with their son's name attached. On Saturday (May 16), the family called on the country star's fans to contribute in a special way, "either doing 3 acts of kindness today or donating $3 to the River Kelly Fund," Amber writes.

Fans stepped up: As of Saturday night (May 16), Amber told Taste of Country that fans had given more than $16,000 in River's memory on his birthday. As of Sunday morning (May 17), more than $18,000 had been raised for the River Kelly Fund.

"Happy birthday in heaven sweet boy. We miss you every second, but we know God has a plan and He will bring light in the dark," she says in a post that has several photos attached:

Since River's passing, Granger and Amber Smith have been candid about the peaks and valleys that come after losing a child and their journey to settle into a new normal. They've also been actively working to inform others about the dangers of open water and small children and how quickly drowning can happen — and how to avoid it. The couple are also parents to two older children, London and Lincoln.

"May we all find joy in life's simple gifts," Amber says. River was a fierce little boy who, according to his mom, loved "dancing, laughing, playing in the dirt, going fast, riding tractors and playing cars."

These Country Singers Have Lost Children, Too