Medicines, IV solutions, medical supplies can all be stockpiled. However, one hopes that their compositions are not changed by all the "activity". Stockpiling all the portable medical supplies we can get our hands on is the best way to go right now.
But won't supplies be needed until new supplies are available? The best thing to do, is to start saving canned goods now. Watch expiration dates and all.
What about potatoes? Grown underground, not subject to wind damage, very dense production per acre .. reproducible Potatoes are supposed to be the thing, per the book Mary's Message to the World, for getting through that first bad year. Yep. Beets, carrots and turnips also.
My thought is that the best thing to store is non-hybrid seeds, plants growing and producing these seeds, etc. on a family or extended family basis. This then won't be snatched away, as it seems to be small potatoes and plus is not a thing easily carried. Would one carry away a worm bed? One would look for sacks of dried beans, etc.
Hydroponics has been specifically mentioned on the list of things to be confiscated, as well as everything that might be useful from farms of any sort. But what if families just set this stuff up in their basements. Actually ordered the supplies to self-sustenance, but set up someplace else other than where the purchase site was. In other words, order or buy in town, set up on the farm.
How about doing all the gathering gradually over the years so it wouldn't be noticeable? However, what a heartbreak to gather stuff together for one's group only to have it taken away last minute! One should have more than one store, etc. Gradual, and whomever does catalog ordering via the mail, etc., should not be the one storing the stuff. Bait and switch. It doesn't take much quantity of seed for a ton of food.