sunking

Good day dudes. I need to start a fund for my college class that will see our money grow over the next 15+ years so that by the time our Silver Jubilee Homecoming comes around, we have a nice budget for donations and celebration events. Are there any recommendations for where I can place our money and make anything better than TD rates? This is going to start at 50K and will be periodically added on to by donations. This has to be placed in an account or fund that has to be signed off by more than one person, just as an added security feature for the class. Thanks.