I collect money. Every month I put $20 in ones into a small cylindrical container I have. I almost put $10 in quarters in as well. It's awesome.
Do you bury it somewhere? My advice would be to bury it until collect enough (usually around $2,500) of them to open an account at a no-load mutual fund like Vanguard, and then once you have an account, regularly purchase more shares in small amounts. If you do that for 30 years, your collection would be pretty nice, and provide you with stability.
[I'm not an investment person, just passing on my thoughts of wise investing. Banks pay nothing in interest these days, so I think this is the only way to grow savings in our current era.]