I'll Remember!

Being that we have a very long growing season here in Florida I have not really played around with starting seeds indoors. I just throw them into the garden and let them do their thing. However, I found these 2 trays that I purchased marigolds in last year for the front yard. It has 18 cups in each one and I thought - why not? After all, this way I'll know it's the plant growing and not weeds. And who knows how many plants I have pulled from the garden thinking they are weeds?
So in went the soil. And out came the seed packets. And I'm saying to myself  "I'll remember" what I planted long enough to grab some paper after I plant them and write it down. Poke the hole, drop in the seed, cover it up.... rinse & repeat 35 more times. Run out and get the paper and pen.... what did i plant? I have the seed packets right here, but where did I put what?
Scrape aside the dirt, look at the seeds.
What is THIS one? I planted several types of watermelon - which one is this? I planted 9 squares of brussel sprouts, which 9?
I finally put together some semblance of a chart. I at least knew which seeds were in which container, just didn't know which square each one was in. Well, that's okay, knowing which container they're in is good enough once they sprout.
But then....
I figure the containers will leak a bit so I'd better put them on something. I found a large lid to a plastic bin, picked them up and set them on it, and didn't pay the slightest attention to which tray I put on first or anything!
LOL, so I have mystery containers for now.