The foliage will usually stay green until the seed are matured. They may look tattered due to heat or drought stress, but once the entire leaf turn yellow, the seed pods should also. I used to use tobacco sacks, the ones with the drawstrings, to capture the seed, but they are difficult to find now, so I cut sections of old pantyhose and tie one end with a twist-tie to make a bag. I have stopped collecting Mayapple seed. Since they also spread by adventious roots, they have taken over one of my flower beds and I am removing root sections for friends that want a start.

For bags go to a craft store or bridal supply. You will find sacks that are used for favors which can be used for your purpose.

Even cheaper get the little translucent satiny bridal gift bags from the dollar store. You get about 3 in a package for a buck.