To get grass seeds in Grounded 2, you need to look up and find specific tall grass plants called "Grass Flowers." These grass flowers have seed clusters or bunches at the top. Use your Omni-Tool Axe to chop down these grass flowers. When the grass flower falls to the ground, there is a chance it will drop grass seeds that you can then pick up. The seeds are important early on because you need them to get the first Shovel upgrade for your Omni-Tool. Summary of steps:

• Look up to spot tall grass plants with seed clusters at the top (called Grass Flowers).
• Approach the Grass Flower and use your Omni-Tool Axe to chop it down.
• When it falls, pick up any grass seeds that drop.
• Use these seeds to trade at any Ominent Terminal for the Omni-Shovel upgrade.

These seeds are mainly used early in the game for the shovel upgrade, which helps in digging up resources like grubs and tougher substances. So focus on cutting down tall grass stalks with visible seed bunches at the top rather than just cutting regular grass at ground level.