@Not-a-user Don't take back Bic Lighters. Take all-metal Zippo lighters, which are all metal. After the fuel runs out, they are worthless, so sell them and say there is a time limit on how long they will work.
@TheBlackCat Hydrogen peroxide may be seen as sorcery, but alchemical directions on how to produce hydrogen peroxide (which you sell to an alchemist) should be safe.
A one-page article in one of the 1632 series anthologies gives alchemical directions on how to make aspirin. Hire a calligrapher to produce a version of these directions. Print them on parchment without a watermark. Sell the directions to local alchemists. An alchemical pain reliever should not change history.
Go through pharmacy catalogs to find which medications are based on herbs. A foxglove preparation for digitalis should be relatively easy to produce. Improving herbal compounds with directions from modern herbals (or selling directions taken from herbals) would help your cash flow.
Download some of the books on how they did stuff in the "olden days" and take those recipes along. Something like the Anarchist's Cookbook should produce some ideas.
I agree with the silk and cotton recommendations, though I would modify it to be spools of thread (and metal needles) instead of bolts of cloth. Spools of thread lend themselves to embroidery. Blue and purple are royal colors because of how expensive those colors are. That's why one shade is called Royal Blue.
One of those all-metal potato peelers could be used to produce potato chips. One look at it and a competent blacksmith could reproduce it, so there is no chance of a charge of "sorcery". You are not limited to potatoes; any other kind of vegetable will do. (Germans though the potato was the "devil's root".)
Cut precious and semi-precious stones. Cut jewels are unknown in the early Middle Ages, but they can figure how to do it easily once they have the idea.
Active yeast cultures which you can sell to the local brewery and bakery are another source of income. People depended on yeast being blown in the window for centuries to start fermentation.
Swords made of Damascus steel should fetch (possibly literally) a king's ransom. It is a limited buyer's market, though.
Scented candles and incense, especially church incense, such as frankincense and myrrh, should be valuable, especially to the local church.