Really anywhere you can gain access to the river you are going to find fish..
For more specific places you could try North Point Park, it has some access, little more East Cambridge. Also where the Muddy comes in around the 2a bridge can produce well.
If you are looking for some pond action you can hit up the Clay Pit Pond and Spy Pond kind of west of Cambridge. Decent fish in both of those. To the south you got Leverette pond, Jamaica pond and Brookline Res.
Should be a good enough start for the area