Really great to know that you have sold some already. What a joy!
I would suggest to use bright yellow or golden paint for letters on black background. Dark reddish letters on black background don't stand out that much.
Secondly, Don't sell the product (eggs), sell something else @$1(Large size sign) to attract them to stop by and raise your eggs prices (to give them a choice of may be two ranges $4 and $6 one to start with ). Make small packs of everything you have on farm - like $1 pack of feathers, A $2 feather tiara etc.
Or better put a Sign FREE FARM TOUR if you've time and may be leave a rooster in a big cage (secured) for attraction and a sign " If you wanna hold the rooster or chicks Just give me a ring" and take them on a free farm tour with more things to sell once they are there.
You never know what works, I can keep on writing when it comes to marketing