I have tested Skyrim immensely and found a bug that effects the plant respawns after you pick them. The issue was introduced after patch 1.3 it effectively broke the respawn system where the plants would disappear after picking them and some plants simply never spawn again.

After over 24 hours of testing I can report that the bug is in Fallout 4.

The easiest place go test the bug is southwest of the Red Rocket Truck Stop. There are some thistle plants there are abut six of them none of them respawn. I am aware that if you stand next to them they emit high levels of rads so I have kept my distance when I check these plants. There is also two wild mutfruit plants in this area that does not respawn.

Also south of the Red Rocket Truck stop there is a mole rat den with two things of glowing fungus and some brain fungus these plants also never respawn again.

I have tested by waiting outside of the cell at the other end of the map for two months in game time I have done this several times.