(CNN) -- Jessica Rees was diagnosed with a brain tumor at age 11, and she and her parents would drive to the hospital every day to receive outpatient treatment. 

"One day we were leaving, and she just simply asked us, 'When do all the other kids come home?'" said her father, Erik. 

When Jessica found out that many of them would have to stay at the hospital, she wanted to help "make them happier, because I know they're going through a lot, too," she said. 

So she started making JoyJars -- containers full of toys, stickers, crayons, anything that might brighten a child's day. 

"She was really particular about what would go in the jars," said her mother, Stacey. "It had to be something cool, it couldn't be cheap or flimsy." 

Jessica created 3,000 JoyJars before she passed away this January. But her parents are carrying on her legacy. 

By the end of 2012, more than 50,000 JoyJars will have been delivered to young cancer patients through the Jessie Rees Foundation. 

"It's what she started, and it's what we'll continue to do," Stacey Rees said. 

Jessica was one of three "Young Wonders" honored this year at "CNN Heroes: An All-Star Tribute." 

"What makes Jessie a Young Wonder is that she cared," her dad said. "And in the midst of a world that says focus on yourself, it's all about you, she said, 'No, it's not.' " 

Watch Jessica's story Donate to her cause 

Will Lourcey 

When Will Lourcey was 6 years old, he asked his parents why a man was holding up a sign that said, "Need a meal." 
How many items they gave by 2012?
By the end of 2012, more than 50,000 JoyJars will have been delivered