Thanks for your suggestion. This has been requested several times previously. Been a while since this idea popped up.
It has its merits, but I personally don't see this working well in DS. Too much room to be abused. A lot of players have multiple accounts and could easily feed items to benefit themselves.
Plus, I have a stack of 2x Elite drops, elite resets, shop refreshes, etc that pile up. But I'd never give up any stamina for any reason. Ever.
If the idea is about scraps, scrolls or gear, well that wouldn't work either. Most guilds I've seen have players who are typically pretty close in their game progression and are caught at same bottle neck of particular items. When I get a key piece like dead eye, fad diet, ligarbalm, sandals, high tea, there's no way I'm giving those up.
Here are some similar threads:
Exchange inside guild
Trading within guilds