Welcome to the Airtable community, Stephanie.
So you have a parent table (the generic PLANTS table) and a child table (MY SEEDS, the plants for which you have seeds). To show a pic of the plant from the parent table (PLANTS), after defining the link to related record and linking a seed to a plant, you would use a second column defined as a “lookup” column.
To link MY SEEDS to PLANTS, start in MY SEEDS (usually good to start in the child table), create a new column and select type “Link to another record.” Select PLANTS, and you’re done.
Now to get the picture, in MY SEEDS, create another column, select type Lookup, and configure the lookup to pull a value from the PLANTS table, Picture column.
Here’s an example using canine breeds and a couple of my own dogs. Notice that one dog, Lulu, is linked to two breeds (Cairn Terrier and Border Terrier) so she has two pictures. Harry on the other hand is linked only to Blue Heeler and that’s the only pic that appears here. The pics are stored in the BREEDS table.
I do have a question for you, though. Do you really need to make this relational? Maybe you do. Maybe it makes sense. But if the seeds are all one-species of plant, then this isn’t a one-to-many (PLANTS to MY SEEDS) relationship, it’s a one-to-one. Do you perhaps have multiple, um, packets of seeds for the same plant, perhaps from different seed sellers? In that case, it would make sense. Otherwise, you could just have a list of plants and something like a check box column to indicate which ones you personally have in your collection.