Memphis , Tennessee ( CNN ) -- They 've been romanticized in movies and songs , but many people really do send messages in a bottle . Chad Pregracke has found 64 of them , accumulating what he believes to be one of the world 's largest collections . The 2013 CNN Hero of the Year stumbled onto them while cleaning up the country 's rivers . Since 1997 , he and volunteers of his nonprofit , Living Lands & Waters , have removed more than 7 million pounds of debris from U.S. waterways . CNN sat down with Pregracke to find out more about his unusual collection and what 's inside each bottle . CNN : How did you come to start this collection ? Chad Pregracke : Well , I found my first one in 1997 , the year I started . There was a large flood on the Mississippi in 1993 , and some guys put a message in a bottle and they threw it in the river and I found it . It had a flag on it . And I just thought it was kind of cool , so I kept it . ... The second year , I found two or three more , and then I started to actually look for them . I try to keep as many as I can . ... It 's pretty cool to find them because ( for the most part ) you never know how far they came , where they came from , who they came from . CNN : How do you find them ? Pregracke : In my work , I see thousands of plastic bottles out there . But I 'm always scanning , looking in every bottle for a piece of paper . You get psyched out a lot because people have stuffed napkins or wrappers in there . You get kind of excited and then , `` Oh no . '' It 's the ultimate thing to find out there . When you 're working , you do n't use that time to open it right then . You put it in ( the ) boat , think about it and then open it up and read it . There 's usually a lot of anticipation for it , especially at a big cleanup . It 's a romantic idea . And truthfully , most of them are n't like a treasure map . Usually they 're more intimate . ... They 're sort of writing to the universe or the one above , just putting their thoughts out there . CNN : What types of messages have you found ? Pregracke : Oh , so many things . Some of them come hundreds of miles down the river or different rivers . ... Some of them have been found three or four times and passed on , and it 'll keep going down the river and down the river . People will sign them and date them . I 've found lottery tickets , parking tickets , dollar bills . We did find a treasure map , but there was no treasure , I checked . I found one from some guys going to the World Series when it was in Kansas City ; that was like 10 years old . I found one from a girl who threw it in a stream in Lawrence , Kansas , and it made it to the Missouri River and then a couple hundred miles into the Mississippi River . That was cool . I found one for voodoo . It said , `` You are bound now , '' and it had a string that pulled the paper tight . ... The newest guy on our board , he was at a cleanup for about 10 minutes and he finds this message in a bottle . It had wax at the top so it would n't leak and all kinds of sparkles and stuff inside . I thought , `` This is going to be a good one . '' We could n't see inside the bottle . I got a knife and opened it . This stuff started blowing all over him . It turned out it was the ashes of somebody . It was like the movie `` The Big Lebowski . '' But it was cool . There was a note about the guy who passed away , and it also had another note that said : `` If anyone finds this , you are so blessed . Thank you so much . '' It was kind of neat that they decided to write a note to someone who might find it someday . CNN : Have you ever gotten in touch with anyone who has sent a message ? Pregracke : Actually , there are fun ones who say , `` If you find this , call me . '' I 've called probably three to five of them over the years . Half of them forget they ever did it . The one that I most remember was a truck driver . He was smart , because he put some rocks in the bottle , which weighs it down , which means the current will carry it versus the wind . Anyway , his message gave his name and phone number , so I called him and said , `` Hey , you threw a message in a bottle . '' And he said , `` I do n't know what you 're talking about . '' And I said : `` Dude , this is you . It 's your name . You must 've thrown it off -- my guess is somewhere near Burlington , Iowa -- and I found it about 90 miles downriver . '' And he said : `` Oh my God , I 'm pulling over . I did that five or six years ago ! '' He got superexcited . It made his week . Do you know a hero ? Nominations are open for 2013 CNN Heroes . CNN : Do you think it 's the world 's largest collection of its kind ? Pregracke : It 's the second-largest . I used to think it was the largest , but I just found out maybe a month ago that this dude down in Texas has 150 of them . He 's a professor , and he has been documenting garbage on the ocean since 1978 -- not picking it up , just documenting it . So his collection is bigger . ... But we have found way more than 64 actually . If volunteers find them and want to keep them , I let them , so we 've probably found about 50 more . I just do n't have them . CNN : Do you have a favorite message ? Pregracke : I do . It 's a song that was written for guitar called `` Lavender Is You . '' It was thrown into the Wabash River and then went into the Ohio River . It 's a love song . It 's sheet music . ... . There 's actually a lot of them that are pretty heavy , you know ? They 're not treasure maps , but they were written to a lost loved one . ... You do n't want to keep it , because it was meant not to be kept . So you just kind of send those on , even though it feels weird letting a bottle go on .
CNN Hero Chad Pregracke has spent the past two years digging up U.S. history . Over that period , he has collected 64 messages in bottles . He 's found lottery tickets , sheet music , people 's letters and even voodoo in the past . Do you know a hero ? Nominations are open for 2013 CNN Heroes .