The city will pick these items up for recycling. Schedule a mattress pickup here -

https://www.cambridgema.gov/Services/mattressrecycling

and clothing/textile pickup here -

https://www.cambridgema.gov/Services/textilesrecycling

There is also a collection bin for clothing and textile recycling at the corner of Broadway and Fayette St. (possibly other locations too but this is the only one I know of).