IMHO, if you take patterns out of a magazine, just mark it with "may have patterns missing". Many companies have the patterns on their web site for free or a nominal cost. If the pattern is missing, so is the picture of the quilt, so I don't think it's a very big deal when the magazine is free. I would still want the magazine to look through and the organization you are donating too can throw it away if they wish. Then I wouldn't feel guilty because I didn't throw it away--that bothers me and seems wasteful. Maybe I'm alone with my feelings, but that's OK.
Sue