Consignment is tricky, especially with an unproven venue.
Business with friends is tricky, it can put a real burden on the friendship.
Don't let the exciting idea of having your work in a shop & the chance to work with your friend interfere with your ability to make good business decisions.
I guess you can get a feel for where I'm starting from, and I follow with thinking it pretty ballsy to ask for half the rent when SHE's asked you to help her fill up some of the space to get the ball rolling in her business and then wants you to provide fixtures for the space (that she'll be using to display her other items for sale) that she'd otherwise have to pay money to purchase...
The display pieces are, in my guess, unlikely to sell because customers will not see them as items for sale, but rather as just fixtures in the store--even if they are marked for sale with prices. And there will be wear and tear on the items decreasing their value while they are used as displays.
I don't know why she'd need an additional 10% for credit card processing (tell her to say hello to Paypal @ 30 cents/transaction + 2.9%, or SquareUp @ 2.75%, both of which can be used with a smart phone or some tablets with internet service and have no monthly account fees using a free gadget the processing company supplies)--that should be part of her overhead that the 15% goes to, though 15% is rather low as consignment pricing goes.
Consignment is usually closer to 40%, so add 10% + 15% and you've got 25% (unless she adds the 10% CC processing fee before she collects 15% commission or vice versa, and that'll inch a little higher--do the math, ask how it will be calculated so you are fully informed) which is still on the low end UNLESS she's using you to foot half her monthly rental bill. And you man the shop without pay? Um, no.
If I'm paying half the rent, I'd want to be half-owner, on the lease, and getting half the profits (I'm NOT at all suggesting going into business with this woman).
If I man the shop a day or two a week I'm either an employee or I'm getting discount on the consignment--like only being charged 15% commission (not commission + rent, and not the same 40% commission as everyone else who is not working there for free).
I would try to back out of it all as gracefully as possible myself--"decided to concentrate my efforts on my garden this spring" or something, and just let it all slide by, even if you never plan to plant a flower, spending less time at the shop each week.
If you do decide to consign in her shop, be sure all the details are spelled out in print & follow consignment laws for your state. Do not let the friendship interfere with good business protection for yourself & your goods... if she pushes back against reasonable preparations, you have your real answer about whether you should participate on any level or not.
Make sure your work isn't the backdrop for what she sells--it's either a featured item for sale or you can pull it from the shop (the ability to pull items should be in the contract).
Make sure you know who is responsible for lost or damaged items (should be in the contract). You should be able rotate your stock if things aren't moving (should be in the contract).
Make sure you know when you'll be paid & how--first of every month? fifteenth? Check mailed? Picked up? (should be in the contract).
Make sure you know who's chunk of the transaction store promotions come out of (she's having a sale in the store--will you expect less or will it come from her cut? ...should be in the contract).
Keep a monthly or quarterly document that you both sign/initial that states what she has of your work, what the selling price should be and/or what the price you expect to be paid is, the date it was added to the store, what has sold, when you will be paid for the goods sold and how much you'll get.
What kind of rate is she offering other folks putting items on consignment in her shop?
Some reading on the topic:
http://www.nolo.com/legal-encyclopedia/consigning-arts-crafts-30281.htmlhttps://www.etsy.com/blog/en/2007/the-ins-and-outs-of-consignment/Do a google search for consignment, download a few contracts that shops have posted on the web and see what they say, compare it to the offer she's putting out there (and to actual consignment laws).