At many parks around Minneapolis. Check this link for a location near you:
https://www.minneapolisparks.org/activities__events/events/earth_day_cleanup/#group_1_219258
Participate in "the annual Minneapolis Earth Day Cleanup and help keep
Minneapolis a beautiful place to live, work, and play! Earth Day Cleanup 2016
up takes place at more than 40 locations throughout Minneapolis. The event has
become the largest community-service project in the city attracting 2,000+
volunteers, annually.
It's easy to get involved in Earth Day Cleanup 2016. No pre-registration
is required! Arrive at any site between 9:30 am and noon, bring a pair of
gloves to pick up trash, and check in at the registration table. A site
coordinator will provide you with gloves (if you did not bring any) and bags,
and instruct you where to go and where to leave trash. Every site has a
coordinator available to assist volunteers and to answer any questions you may
have."