Taraxacums are notorious cross breeders and there are several sections each with micro species. They are very difficult to id, especially with no foliage or habit to see. If the stem was soft and hollow with milky sap which stains fingers brown it probably is a dandelion of some sort. Well nigh impossible to pin down further. I have been unable to establish whether T albidum occurs in Germany. It is a Japanese native. I think you will get more responses to your queries if you post each as a new question. People may look at this thread, think they have already checked it out, and not realise there is a new question at the end.

Thanks, floral_uk. That seems like a strong possibility, though none of the flowers I'm looking at seem to open as much as Cardamine's flowers. Maybe I need to give them a few days. The plants are about 9" tall which is about the same for Cardamine. I see this Cardamine is sometimes called "Sand bittercress" which would accord with these plants growing in virtual gravel. Here are several photos I just took (some of which are virtual duplicates but they look beautiful!) I'll get a good photo of the basal leaves later today.

Embothrium - the plants are growing in SW lower Michigan but the "surprise" seeds are all non-native, naturalized species, both for Michigan and the US. floral_uk z.8/9 SW UK - I had to look up that one - "etiolated" - so yes, it is growing in partial shade and it does appear to be Lobularia maritima, thanks for the tip.

Both answers are correct. I was relieved to learn this was Sherardia. I went through every species of Galium and nothing matched. Either it's not here in my local area, or I've been mistaking it for Galium. BONAP has this listed as Galium sherardia. That name,Galium sherardia was given by Krause in the nineteenth century. This species has had several names since including Asperula, [ 10 synonyms]. Linaeus, adapted the name, already given to it, in honor of William Sherard. Sherard was a botanist, and was classifying plants prior to Linaeus. I read that the flower color, flower shapes, and floral bracts of Sherardia were the reason it wasn't lumped into Galium' but I think the main difference is the floral bracts. I've seen photos of Galium species with red flowers, and then we have Galium trifidum with 3 petaled flowers, but still remaining in Galium? I don't see any significant difference in the flowers of Sherardia compared to Galium flowers, am I missing something? So, the question, are bracts more of a morphological leap then petal count, and deserving of a move to a monotypic genus? Cool link, if you like the history of taxonomy. https://herbaria.plants.ox.ac.uk/bol/plants400/Profiles/st/Sherardia BONAP Galium sherardia Galium trifidum Galium arkansanum Wouldn't mind having this as a weed. Weakley (2020) Flora of the Southeastern United States. Galium sherardia. ...usually treated as a monotypic genus, buy Soza and Olmstead (2010) show Sherardia to be deeply embedded within a paraphyletic Galium. Gerould Wilhelm ( Plants of the Chicago Region, Flora of the Chicago Region), Sherardia arvensis. Wilhelm also goes with Prenanthes instead of Nabalus. It's hard to decide which of two great botanists is more correct, but I usually side with Weakley, and most native plant people here in northern Illinois swear by Wilhelm, so I'background? Perenn gave the genus. So I have to wonder what Linnaeus would have named it, if he had encountered it as a new, unknown specimen? Galium bracteata? Galium verticillata? He might have even wanted to rename it back then, but didn't want to upset the guys who already had named it in another guy's honor.