Preheat oven to 350F and lightly oil 2 small loaf pans or one medium-sized loaf pan. Set aside.Add onion, garlic, mushrooms and oil to a pan. Saute on medium heat until lightly browned.Combine ground flaxseed with warm water in a small bowl and allow to sit for at least 5 minutes.Meanwhile, add sunflower seeds to the bowl of your food processor. Process until there are small bits, the size of hemp hearts. Add hemp hearts, almond flour, spices, and salt. Pulse lightly, to break up the hemp hearts a little bit and combine everything.Transfer seed mixture to a bowl. Set aside. Transfer sauteed mixture to your food processor and give it a little whirl to break things down.Drop sauteed ingredients into a large bowl. Add processed seeds. Stir to combine, then add flaxseed mixture. Stir until everything is coated in the mixture. It should be a thick paste.Divide mixture and press into loaf pans. Transfer to oven and bake for 40-45 minutes, until a toothpick inserted comes out clean. Remove from oven and allow to cool for 1-2 hours before running a knife along the edge of the loaf pan and lifting out the loaf. You can also serve from inside the pan.