Not a problem. The only ones that I've worked with that absolutely needed to be sown fresh or pretty close to dehiscence were Phalaenopsis and Coryanthes. Cypripedium candidum, which I'm actually doing my dissertation on, have to be green pod sown or else they build up dormancy mechanisms. These can be overcome but it takes additional steps. The tropical seed that I mentioned actually dies (or goes into a dormancy we don't know about) and can't be recovered. Although many labs will prefer green pods I'm sure they won't have a problem with properly stored and dried seed. If you have the ability, pick up some silica desiccant and a cigar hygrometer. Place the seeds with some desiccant and the hygrometer in a jar and keep them in there until the hygrometer reads 10-20%. The seeds can of course be in some sort of container such as a paper envelope or open microcentrifuge tube. When the seeds dry out properly the container can be closed and stored at 3-5 c for at least 5-10 yrs. with very little loss in germination rate. Let me know if you need anything else.