i posted a forum about this a bit ago
the answers were either hide in plain sight or burry them below the ground (not my ideas, but others that i dont remember, my forum was called "keeping the secert" if you want a closer look
it was easier on me, i actually was interested in rocks and crystals long before, so i had a collection already! :D now when i get things, people think i just collect :)
try showing interest
another thing is try your hand at cooking, dont go nuts but ask for simpler things like sage (whites easiest in my case to get) or offer a meal idea using it
become known to them as- our well rounded child who likes crystals and cooking, not a witch :) good luck!